Use of Alkyl Perfluoroalkene Ethers and Mixtures Thereof in High Temperature Heat Pumps

ABSTRACT

Disclosed herein is a method for producing heating in a high temperature heat pump having a heat exchanger. The method comprises extracting heat from a working fluid, thereby producing a cooled working fluid wherein said working fluid comprises at least one alkyl perfluoroalkene ether. Also disclosed is a method of raising the maximum feasible condenser operating temperature in a high temperature heat pump apparatus. The method comprises charging the high temperature heat pump with a working fluid comprising at least one alkyl perfluoroalkene ether. Also disclosed is a high temperature heat pump apparatus. The apparatus contains a working fluid comprising at least one alkyl perfluoroalkene ether. Also disclosed is a composition comprising at least one alkyl perfluoroalkene ether, and specialized additives or lubricants for use in a high temperature heat pump.

FIELD OF THE INVENTION

This invention relates to methods and systems having utility in numerousapplications, and in particular, in high temperature heat pumps.

BACKGROUND OF THE INVENTION

Current trends shaping the global energy landscape suggest an expandingutilization of low temperature heat (i.e. heat at temperatures lowerthan about 250° C.) in the near future. Such heat may be recovered fromvarious commercial or industrial operations, can be extracted fromgeothermal or hydrothermal reservoirs or can be generated through solarcollectors. Motivation for low temperature heat utilization is providedby increasing energy prices and a growing awareness of the environmentalimpacts, in general, and the threat to the earth's climate, inparticular, from the use of fossil fuels.

Elevation of the temperature of available heat through high temperaturemechanical compression heat pumps (HTHPs) to meet heating requirementsis one promising approach for the use of low temperature heat. Heatpumps operating according to a reverse Rankine cycle require the use ofworking fluids. Commercially available working fluids that are used orcould be used for HTHPs (e.g. HFC-245fa, Vertrel® XF, HFC-365mfc) arecoming under increasing scrutiny because of their relatively high GlobalWarming Potential (GWP). Clearly, there is an increasing need for moreenvironmentally sustainable working fluids for HTHPs.

The use of zero-ODP, low GWP working fluids based on hydrofluoroolefins(HFOs) for high temperature heat pumps has been previously disclosed.However, the critical temperatures of previously disclosed HFO-basedworking fluids limit the maximum practical condensing temperatures thatcould be delivered by a heat pump operating according to theconventional reverse Rankine cycle to about 160° C.

The compositions of the present invention are part of a continued searchfor the next generation of low global warming potential materials. Suchmaterials must have low environmental impact, as measured by low globalwarming potential and zero ozone depletion potential. New heat pump andhigh temperature heat pump working fluids are needed.

SUMMARY OF THE INVENTION

This invention discloses low GWP working fluids with criticaltemperatures sufficiently high to enable high temperature heat pumps todeliver condensing temperatures approaching or even exceeding 230° C.

Embodiments of the present invention involve alkyl perfluoroalkeneethers, either alone or in combination with one or more other compoundsas described in detail herein below.

In accordance with this invention, a method for producing heating in ahigh temperature heat pump having a heat exchanger is provided. Themethod comprises extracting heat from a working fluid, thereby producinga cooled working fluid wherein said working fluid comprises at least onealkyl perfluoroalkene ether.

Also in accordance with this invention, a method of raising thecondenser operating temperature in a high temperature heat pumpapparatus is provided. The method comprises charging the hightemperature heat pump with a working fluid comprising at least one alkylperfluoroalkene ether.

Also in accordance with this invention, a high temperature heat pumpapparatus is provided. The apparatus contains a working fluid comprisingat least one alkyl perfluoroalkene ether.

Also in accordance with this invention, a composition for use in hightemperature heat pumps is provided. The composition comprises (i) aworking fluid consisting essentially of at least one alkylperfluoroalkene ether; and (ii) a stabilizer to prevent degradation attemperatures of 55° C. or above; or (iii) a lubricant suitable for useat 55° C. or above, or both (ii) and (iii).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of one embodiment of a flooded evaporatorheat pump apparatus according to the present invention.

FIG. 2 is a schematic diagram of one embodiment of a direct expansionheat pump apparatus according to the present invention.

FIG. 3 is a schematic diagram of a cascade heating pump system accordingto the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Before addressing details of embodiments described below, some terms aredefined or clarified.

Global warming potential (GWP) is an index for estimating relativeglobal warming contribution due to atmospheric emission of a kilogram ofa particular greenhouse gas compared to emission of a kilogram of carbondioxide. GWP can be calculated for different time horizons showing theeffect of atmospheric lifetime for a given gas. The GWP for the 100 yeartime horizon is commonly the value referenced.

Ozone depletion potential (ODP) is defined in “The Scientific Assessmentof Ozone Depletion, 2002, A report of the World MeteorologicalAssociation's Global Ozone Research and Monitoring Project,” section1.4.4, pages 1.28 to 1.31 (see first paragraph of this section). ODPrepresents the extent of ozone depletion in the stratosphere expectedfrom a compound on a mass-for-mass basis relative tofluorotrichloromethane (CFC-11).

Refrigeration capacity (sometimes referred to as cooling capacity) is aterm to define the change in enthalpy of a refrigerant or working fluidin an evaporator per unit mass of refrigerant or working fluidcirculated. Volumetric cooling capacity refers to the amount of heatremoved by the refrigerant or working fluid in the evaporator per unitvolume of refrigerant vapor exiting the evaporator. The refrigerationcapacity is a measure of the ability of a refrigerant, working fluid orheat transfer composition to produce cooling. Therefore, the higher thevolumetric cooling capacity of the working fluid, the greater thecooling rate that can be produced at the evaporator with the maximumvolumetric flow rate achievable with a given compressor. Cooling raterefers to the heat removed by the refrigerant in the evaporator per unittime.

Similarly, volumetric heating capacity is a term to define the amount ofheat supplied by the refrigerant or working fluid in the condenser perunit volume of refrigerant or working fluid vapor entering thecompressor. The higher the volumetric heating capacity of therefrigerant or working fluid, the greater the heating rate that isproduced at the condenser with the maximum volumetric flow rateachievable with a given compressor.

Coefficient of performance (COP) is the amount of heat removed in theevaporator divided by the energy required to operate the compressor. Thehigher the COP, the higher the energy efficiency. COP is directlyrelated to the energy efficiency ratio (EER), that is, the efficiencyrating for refrigeration or air conditioning equipment at a specific setof internal and external temperatures.

As used herein, a heat transfer medium (also referred to herein as aheating medium) comprises a composition used to carry heat from a bodyto be cooled to the chiller evaporator or from the chiller condenser toa cooling tower or other configuration where heat can be rejected to theambient.

As used herein, a working fluid comprises a compound or mixture ofcompounds that function to transfer heat in a cycle wherein the workingfluid undergoes a phase change from a liquid to a gas and back to aliquid in a repeating cycle.

Subcooling is the reduction of the temperature of a liquid below thatliquid's saturation point for a given pressure. The saturation point isthe temperature at which a vapor composition is completely condensed toa liquid (also referred to as the bubble point). But subcoolingcontinues to cool the liquid to a lower temperature liquid at the givenpressure. By cooling a liquid below the saturation temperature, the netrefrigeration capacity can be increased. Subcooling thereby improvesrefrigeration capacity and energy efficiency of a system. Subcool amountis the amount of cooling below the saturation temperature (in degrees)or how far below its saturation temperature a liquid composition iscooled.

Superheat is a term that defines how far above its saturation vaportemperature (the temperature at which, if the composition is cooled, thefirst drop of liquid is formed, also referred to as the “dew point”) avapor composition is heated.

Temperature glide (sometimes referred to simply as “glide”) is theabsolute value of the difference between the starting and endingtemperatures of a phase-change process by a refrigerant within acomponent of a refrigerant system, exclusive of any subcooling orsuperheating. This term may be used to describe condensation orevaporation of a near azeotrope or non-azeotropic composition.

An azeotropic composition is a mixture of two or more differentcomponents which, when in liquid form under a given pressure, will boilat a substantially constant temperature, which temperature may be higheror lower than the boiling temperatures of the individual components, andwhich will provide a vapor composition essentially identical to theoverall liquid composition undergoing boiling. (see, e.g., M. F. Dohertyand M. F. Malone, Conceptual Design of Distillation Systems, McGraw-Hill(New York), 2001, 185-186, 351-359).

Accordingly, the essential features of an azeotropic composition arethat at a given pressure, the boiling point of the liquid composition isfixed and that the composition of the vapor above the boilingcomposition is essentially that of the overall boiling liquidcomposition (i.e., no fractionation of the components of the liquidcomposition takes place). It is also recognized in the art that both theboiling point and the weight percentages of each component of theazeotropic composition may change when the azeotropic composition issubjected to boiling at different pressures. Thus, an azeotropiccomposition may be defined in terms of the unique relationship thatexists among the components or in terms of the compositional ranges ofthe components or in terms of exact weight percentages of each componentof the composition characterized by a fixed boiling point at a specifiedpressure.

For the purpose of this invention, an azeotrope-like (or nearazeotropic) composition means a composition that behaves substantiallylike an azeotropic composition (i.e., has constant boilingcharacteristics or a tendency not to fractionate upon boiling orevaporation). Hence, during boiling or evaporation, the vapor and liquidcompositions, if they change at all, change only to a minimal ornegligible extent. This is to be contrasted with non-azeotrope-likecompositions in which during boiling or evaporation, the vapor andliquid compositions change to a substantial degree.

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a composition,process, method, article, or apparatus that comprises a list of elementsis not necessarily limited to only those elements but may include otherelements not expressly listed or inherent to such composition, process,method, article, or apparatus. Further, unless expressly stated to thecontrary, “or” refers to an inclusive or and not to an exclusive or. Forexample, a condition A or B is satisfied by any one of the following: Ais true (or present) and B is false (or not present), A is false (or notpresent) and B is true (or present), and both A and B are true (orpresent).

The transitional phrase “consisting of” excludes any element, step, oringredient not specified. If in the claim such would close the claim tothe inclusion of materials other than those recited except forimpurities ordinarily associated therewith. When the phrase “consistsof” appears in a clause of the body of a claim, rather than immediatelyfollowing the preamble, it limits only the element set forth in thatclause; other elements are not excluded from the claim as a whole.

The transitional phrase “consisting essentially of” is used to define acomposition, method or apparatus that includes materials, steps,features, components, or elements, in addition to those literallydisclosed provided that these additional included materials, steps,features, components, or elements do materially affect the basic andnovel characteristic(s) of the claimed invention. The term ‘consistingessentially of’ occupies a middle ground between “comprising” and‘consisting of’.

Where applicants have defined an invention or a portion thereof with anopen-ended term such as “comprising,” it should be readily understoodthat (unless otherwise stated) the description should be interpreted toalso describe such an invention using the terms “consisting essentiallyof” or “consisting of.”

Also, use of “a” or “an” are employed to describe elements andcomponents described herein. This is done merely for convenience and togive a general sense of the scope of the invention. This descriptionshould be read to include one or at least one and the singular alsoincludes the plural unless it is obvious that it is meant otherwise.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of embodiments of the present invention, suitablemethods and materials are described below. All publications, patentapplications, patents, and other references mentioned herein areincorporated by reference in their entirety, unless a particular passageis cited. In case of conflict, the present specification, includingdefinitions, will control. In addition, the materials, methods, andexamples are illustrative only and not intended to be limiting.

The alkyl perfluoroalkene ether working fluids disclosed herein for usein the method to produce heating may be prepared by contacting aperfluoroalkene, such as perfluoro-3-heptene, pefluoro-2-heptene,perfluoro-2-hexene, perfluoro-3-hexene, or perfluoro-2-pentene with analcohol in the presence of a strong base optionally in the presence of aphase transfer catalyst, as described in detail in U.S. Pat. No.8,399,713. For example, perfluoro-3-heptene may be reacted with analcohol such as methanol or ethanol, or mixtures thereof, in thepresence of an aqueous solution of a strong base to produce unsaturatedfluoroethers.

In one embodiment, the products from the reaction of perfluoro-3-heptenewith methanol comprise 5-methoxyperfluoro-3-heptene,3-methoxyperfluoro-3-heptene, 4-methoxyperfluoro-2-heptene and3-methoxyperfluoro-2-heptene.

In one embodiment, the products from the reaction of perfluoro-2-pentenewith methanol comprise 4-methoxyperfluoro-2-pentene,2-methoxyperfluoro-2-pentene, 3-methoxyperfluoro-2-pentene, and2-methoxyperfluoro-3-pentene.

In one embodiment, the products from the reaction of perfluoro-2-octenewith methanol comprise cis- and trans-2-methoxyperfluoro-2-octene and2-methoxyperfluoro-3-octene.

High Temperature Heat Pump Methods

In accordance with this invention, a method is provided for producingheating in a high temperature heat pump having a condenser wherein avapor working fluid is condensed to heat a heat transfer medium and theheated heat transfer medium is transported out of the condenser to abody to be heated. The method comprises condensing a vapor working fluidin a condenser, thereby producing a liquid working fluid wherein saidvapor and liquid working fluid comprises at least one alkylperfluoroalkene ether.

In one embodiment is provided a method for producing heating in a hightemperature heat pump comprising extracting heat from a working fluid,thereby producing a cooled working fluid wherein said working fluidcomprises at least one alkyl perfluoroalkene ether. Of note are methodswherein the working fluid consists essentially of at least one alkylperfluoroalkene ether. Also of note are methods wherein the workingfluid consists of at least one alkyl perfluoroalkene ether.

In one embodiment, the method for producing heating uses a working fluidcomprising at least one alkyl perfluoroalkene ether.

In one embodiment, the working fluid comprises at least one alkylperfluoroalkene ether selected from the group consisting of:

-   -   a) compounds of formula CF₃(CF₂)_(x)CF═CFCF(OR)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)C(OR)═CFCF₂(CF₂)_(y)CF₃,        CF₃CF═CFCF(OR)(CF₂)_(x)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)CF═C(OR)CF₂(CF₂)_(y)CF₃, or mixtures thereof,        wherein R can be either CH₃, C₂H₅ or mixtures thereof, and        wherein x and y are independently 0, 1, 2 or 3, and wherein        x+y=0, 1, 2 or 3 having the formula;    -   b) compounds of formulas CF₃(CF₂)_(x)CF═CFCF(OR)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)C(OR)═CFCF₂(CF₂)_(y)CF₃,        CF₃CF═CFCF(OR)(CF₂)_(x)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)CF═C(OR)CF₂(CF₂)_(y)CF₃, and mixtures thereof;        wherein x and y are independently 0, 1, 2, 3 or 4 and wherein        x+y=0, 1, 2, 3 or 4; and wherein R is        2,2,3,3-tetrafluoro-1-propyl, 2,2,3,3,3-pentafluoro-1-propyl,        2,2,2-trifluoro-1-ethyl, 2,2,3,3,4,4,5,5-octafluoro-1-pentyl, or        1,1,1,3,3,3-hexafluoro-2-propyl; and    -   c) mixtures of compounds from (a) and (b).

In one embodiment of the method for producing heating, the alkylperfluoroalkene ethers comprise 5-methoxyperfluoro-3-heptene,3-methoxyperfluoro-3-heptene, 4-methoxyperfluoro-2-heptene,3-methoxyperfluoro-2-heptene, and mixtures thereof.

In one embodiment of the method for producing heating, the alkylperfluoroalkene ethers comprise 4-methoxyperfluoro-2-pentene,2-methoxyperfluoro-2-pentene, 3-methoxyperfluoro-2-pentene,2-methoxyperfluoro-3-pentene, and mixtures thereof.

In one embodiment of the method for producing heating, the alkylperfluoroalkene ethers comprise cis- andtrans-2-methoxyperfluoro-2-octene, 2-methoxyperfluoro-3-octene, andmixtures thereof.

In one embodiment of the method for producing heating, the working fluidfurther comprises at least one compound selected fromhydrofluorocarbons, hydrochlorocarbons, hydrofluoroethers,hydrofluoroolefins, hydrochlorofluorolefins, siloxanes, hydrocarbons,alcohols, perfluoropolyethers, and mixtures thereof.

In one embodiment of the method for producing heating, the working fluidcomprises azeotropic or near-azeotropic mixtures. In one embodiment, theazeotropic or near azeotropic mixture comprises at least one methylperfluoroheptene ether and at least one compound selected from the groupconsisting of heptane, ethanol, and trans-1,2-dichloroethene. In anotherembodiment, the azeotropic or near azeotropic mixture comprises at leastone methyl perfluoropentene ether and at least one compound selectedfrom the group consisting of trans-1,2-dichloroethene, methanol,ethanol, 2-propanol, cyclopentane, ethyl formate, methyl formate, and1-bromopropane.

In yet another embodiment of the method for producing heating, theworking fluid comprises at least one alkyl perfluoroalkene ether andoptionally one or more fluids selected from the group consisting ofHFC-161, HFC-32, HFC-125, HFC-143a, HFC-245cb, HFC-134a, HFC-134,HFC-227ea, HFC-236ea, HFC-245fa, HFC-245eb, HFC-365mfc, HFC-4310mee,HFO-1234yf, HFO-1234ze-E, HFO-1234ze-Z, HFO-1336mzz-E, HFO-1336mzz-Z,HFO-1234ye-E or Z (1,2,3,3-tetrafluoropropene), HFO-1438mzz-E,HFO-1438mzz-Z, HFO-1438ezy-E, HFO-1438ezy-Z, HFO-1336yf, HFO-1336ze-E,HFO-1336ze-Z, HCFO-1233zd-E, HCFO-1233zd-Z, HCFO-1233xf, HFE-7000 (alsoknown as HFE-347mcc or n-C₃F₇OCH₃), HFE-7100 (also known as HFE-449mcccor C₄F₉OCH₃), HFE-7200 (also known as HFE-569mccc or C₄F₉OC₂H₅),HFE-7500 (also known as3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-trifluoromethyl-hexaneor (CF₃)₂CFCF(OC₂H₅)CF₂CF₂CF₃),1,1,1,2,2,4,5,5,5-nonafluoro-4-(trifluoromethyl)-3-pentanone (sold underthe trademark Novec™ 1230 by 3M, St. Paul, Minn., USA),octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane,octamethyltrisiloxane (OMTS), hexamethyldisiloxane (HMDS), n-pentane,isopentane, cyclopentane, hexanes, cyclohexane, heptanes, and toluene.

Also of particular utility in the method for producing heating are thoseembodiments wherein the working fluid has a low GWP.

In one embodiment of the method for producing heating, the heatexchanger is selected from the group consisting of a supercriticalworking fluid cooler and a condenser.

In some embodiments of the method for producing heating, the hightemperature heat pump operates at heat exchanger temperatures greaterthan about 55° C. In another embodiment, the high temperature heat pumpoperates at heat exchanger temperatures greater than about 60° C. Inanother embodiment, the high temperature heat pump operates at heatexchanger temperatures greater than about 65° C. In another embodiment,the high temperature heat pump operates at heat exchanger temperaturesgreater than about 75° C. In another embodiment, the high temperatureheat pump operates at heat exchanger temperatures greater than about100° C. In another embodiment, the high temperature heat pump operatesat heat exchanger operating temperatures greater than about 120° C.

In some embodiments of the method for producing heating, the hightemperature heat pump operates at condenser or supercritical workingfluid cooler temperatures greater than about 55° C. In anotherembodiment, the high temperature heat pump operates at condenser orsupercritical working fluid cooler temperatures greater than about 60°C. In another embodiment, the high temperature heat pump operates atcondenser or supercritical working fluid cooler temperatures greaterthan about 65° C. In another embodiment, the high temperature heat pumpoperates at condenser or supercritical working fluid cooler temperaturesgreater than about 75° C. In another embodiment, the high temperatureheat pump operates at condenser or supercritical working fluid coolertemperatures greater than about 100° C. In another embodiment, the hightemperature heat pump operates at condenser or supercritical workingfluid cooler operating temperatures greater than about 120° C.

In one embodiment of the method for producing heating, the methodfurther comprises passing a first heat transfer medium through the heatexchanger, whereby said extraction of heat heats the first heat transfermedium, and passing the heated first heat transfer medium from the heatexchanger to a body to be heated.

A body to be heated may be any space, object or fluid that may beheated. In one embodiment, a body to be heated may be a room, building,or the passenger compartment of an automobile. Alternatively, in anotherembodiment, a body to be heated may be a heat transfer medium or heattransfer fluid.

In one embodiment of the method for producing heating, the first heattransfer medium is water and the body to be heated is water. In anotherembodiment, the first heat transfer medium is water and the body to beheated is air for space heating. In another embodiment, the first heattransfer medium is an industrial heat transfer liquid and the body to beheated is a chemical process stream.

In another embodiment of the method for producing heating, the method toproduce heating further comprises compressing the working fluid in adynamic (e.g. axial or centrifugal) compressor or a positivedisplacement (e.g., reciprocating, screw or scroll) compressor. Inanother embodiment, the dynamic compressor is a centrifugal compressor.In another embodiment, the dynamic compressor is a screw compressor. Inanother embodiment, the dynamic compressor is a scroll compressor.

In another embodiment of the method for producing heating, the method toproduce heating further comprises compressing the working fluid vapor ina centrifugal compressor.

In one embodiment of the method for producing heating, the heating isproduced in a heat pump having a condenser comprising passing a heattransfer medium to be heated through said condenser, thus heating theheat transfer medium. In one embodiment, the heat transfer medium isair, and the heated air from the condenser is passed to a space to beheated. In another embodiment, the heat transfer medium is a portion ofa process stream, and the heated portion is returned to the process.

In some embodiments of the method for producing heating, the heattransfer medium (or heating medium) may be selected from water or glycol(such as ethylene glycol or propylene glycol). Of particular note is anembodiment wherein the first heat transfer medium is water and the bodyto be cooled is air for space cooling.

In another embodiment of the method for producing heating, the heattransfer medium may be an industrial heat transfer liquid, wherein thebody to be heated is a chemical process stream, which includes processlines and process equipment such as distillation columns. Of note areindustrial heat transfer liquids including ionic liquids, various brinessuch as aqueous calcium or sodium chloride, glycols such as propyleneglycol or ethylene glycol, methanol, and other heat transfer media suchas those listed in Chapter 4 of the 2006 ASHRAE Handbook onRefrigeration.

In one embodiment, the method for producing heating comprises extractingheat in a flooded evaporator high temperature heat pump as describedabove with respect to FIG. 1. In this method, the liquid working fluidis evaporated to form a working fluid vapor in the vicinity of a firstheat transfer medium. The first heat transfer medium is a warm liquid,such as water, which is transported into the evaporator via a pipe froma low temperature heat source. The warm liquid is cooled and is returnedto the low temperature heat source or is passed to a body to be cooled,such as a building. The working fluid vapor is then condensed in thevicinity of a second heat transfer medium, which is a chilled liquidwhich is brought in from the vicinity of a body to be heated (heatsink). The second heat transfer medium cools the working fluid such thatit is condensed to form a liquid working fluid. In this method a floodedevaporator heat pump may also be used to heat domestic or service wateror a process stream.

In another embodiment, the method for producing heating comprisesproducing heating in a direct expansion high temperature heat pump asdescribed above with respect to FIG. 2. In this method, the liquidworking fluid is passed through an evaporator and evaporates to producea working fluid vapor. A first liquid heat transfer medium is cooled bythe evaporating working fluid. The first liquid heat transfer medium ispassed out of the evaporator to a low temperature heat source or a bodyto be cooled. The working fluid vapor is then condensed in the vicinityof a second heat transfer medium, which is a chilled liquid which isbrought in from the vicinity of a body to be heated (heat sink). Thesecond heat transfer medium cools the working fluid such that it iscondensed to form a liquid working fluid. In this method, a directexpansion heat pump may also be used to heat domestic or service wateror a process stream.

In one embodiment of the method for producing heating, the hightemperature heat pump includes a compressor which is a centrifugalcompressor.

In one embodiment of the method for producing heat, heat is exchangedbetween at least two heating stages, the method comprises absorbing heatin a working fluid in a heating stage operated at a selected condensingtemperature and transferring this heat to the working fluid of anotherheating stage operated at a higher condensing temperature; wherein theworking fluid of the heating stage operated at the higher condensingtemperature comprises at least one alkyl perfluoroalkene ether.

In one embodiment, a method for producing heating in a high temperatureheat pump is provided, wherein heat is exchanged between at least twostages arranged in a cascade configuration, comprising absorbing heat ata selected lower temperature in a first working fluid in a first cascadestage and transferring this heat to a second working fluid of a secondcascade stage that supplies heat at a higher temperature; wherein thesecond working fluid comprises at least one alkyl perfluoroalkene ether.In another embodiment, the heat supplied in the second cascade stage isat a temperature of at least 150° C.

In another embodiment of the invention is disclosed a method of raisingthe condenser operating temperature in a high temperature heat pumpapparatus comprising charging the high temperature heat pump with aworking fluid comprising at least one alkyl perfluoroalkene ether.

Use of alkyl perfluoroalkene ethers in high temperature heat pumpsincreases the capability of these heat pumps because it allows operationat condenser temperatures higher than achievable with working fluidsused in similar systems today.

In one embodiment, the method of raising the condenser operatingtemperature in a high temperature heat pump apparatus uses a workingfluid comprising at least one alkyl perfluoroalkene ether.

In one embodiment of the method of raising the condenser operatingtemperature, the working fluid comprises at least one alkylperfluoroalkene ether selected from the group consisting of:

-   -   a) compounds of formula CF₃(CF₂)_(x)CF═CFCF(OR)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)C(OR)═CFCF₂(CF₂)_(y)CF₃,        CF₃CF═CFCF(OR)(CF₂)_(x)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)CF═C(OR)CF₂(CF₂)_(y)CF₃, or mixtures thereof,        wherein R can be either CH₃, C₂H₅ or mixtures thereof, and        wherein x and y are independently 0, 1, 2 or 3, and wherein        x+y=0, 1, 2 or 3 having the formula;    -   b) compounds of formulas CF₃(CF₂)_(x)CF═CFCF(OR)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)C(OR)═CFCF₂(CF₂)_(y)CF₃,        CF₃CF═CFCF(OR)(CF₂)_(x)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)CF═C(OR)CF₂(CF₂)_(y)CF₃, and mixtures thereof;        wherein x and y are independently 0, 1, 2, 3 or 4 and wherein        x+y=0, 1, 2, 3 or 4; and wherein R is        2,2,3,3-tetrafluoro-1-propyl, 2,2,3,3,3-pentafluoro-1-propyl,        2,2,2-trifluoro-1-ethyl, 2,2,3,3,4,4,5,5-octafluoro-1-pentyl, or        1,1,1,3,3,3-hexafluoro-2-propyl; and    -   c) mixtures of compounds from (a) and (b).

In one embodiment of the method of raising the maximum feasiblecondenser operating temperature, the alkyl perfluoroalkene etherscomprise at least one of 5-methoxyperfluoro-3-heptene,3-methoxyperfluoro-3-heptene, 4-methoxyperfluoro-2-heptene,3-methoxyperfluoro-2-heptene, or mixtures thereof.

In one embodiment of the method of raising the condenser operatingtemperature, the alkyl perfluoroalkene ethers comprise at least one of4-methoxyperfluoro-2-pentene, 2-methoxyperfluoro-2-pentene,3-methoxyperfluoro-2-pentene, 2-methoxyperfluoro-3-pentene, or mixturesthereof.

In one embodiment of the method of raising the condenser operatingtemperature, the alkyl perfluoroalkene ethers comprise at least one ofcis- and trans-2-methoxyperfluoro-2-octene, 2-methoxyperfluoro-3-octene,or mixtures thereof.

In one embodiment of the method of raising the condenser operatingtemperature, the working fluid further comprises at least one compoundselected from hydrofluorocarbons, hydrochlorocarbons, hydrofluoroethers,hydrofluoroolefins, hydrochlorofluorolefins, siloxanes, hydrocarbons,alcohols, perfluoropolyethers, and mixtures thereof.

In one embodiment of the method of raising the condenser operatingtemperature, the working fluid comprises azeotropic or near-azeotropicmixtures. In one embodiment, the azeotropic or near azeotropic mixturecomprises at least one methyl perfluoroheptene ether and at least onecompound selected from the group consisting of heptane, ethanol, andtrans-1,2-dichloroethene as disclosed in. In another embodiment, theazeotropic or near azeotropic mixture comprises at least one methylperfluoropentene ether and at least one compound selected from the groupconsisting of trans-1,2-dichloroethene, methanol, ethanol, 2-propanol,cyclopentane, ethyl formate, methyl formate, and 1-bromopropane.

In yet another embodiment of the method of raising the condenseroperating temperature, the working fluid comprises at least one alkylperfluoroalkene ether and optionally one or more fluids selected fromthe group consisting of HFC-161, HFC-32, HFC-125, HFC-143a, HFC-245cb,HFC-134a, HFC-134, HFC-227ea, HFC-236ea, HFC-245fa, HFC-245eb,HFC-365mfc, HFC-4310mee, HFO-1234yf, HFO-1234ze-E, HFO-1234ze-Z,HFO-1336mzz-E, HFO-1336mzz-Z, HFO-1234ye-E or Z(1,2,3,3-tetrafluoropropene), HFO-1438mzz-E, HFO-1438mzz-Z,HFO-1438ezy-E, HFO-1438ezy-Z, HFO-1336yf, HFO-1336ze-E, HFO-1336ze-Z,HCFO-1233zd-E, HCFO-1233zd-Z, HCFO-1233xf, HFE-7000 (also known asHFE-347mcc or n-C₃F₇OCH₃), HFE-7100 (also known as HFE-449mccc orC₄F₉OCH₃), HFE-7200 (also known as HFE-569mccc or C₄F₉OC₂H₅), HFE-7500(also known as3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-trifluoromethyl-hexaneor (CF₃)₂CFCF(OC₂H₅)CF₂CF₂CF₃),1,1,1,2,2,4,5,5,5-nonafluoro-4-(trifluoromethyl)-3-pentanone (sold underthe trademark Novec™ 1230 by 3M, St. Paul, Minn., USA),octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane,octamethyltrisiloxane (OMTS), hexamethyldisiloxane (HMDS), n-pentane,isopentane, cyclopentane, hexanes, cyclohexane, heptanes, and toluene.

Also of particular utility in the method of raising the condenseroperating temperature are those embodiments wherein the working fluidhas a low GWP.

When CFC-114 is used as the working fluid in a high temperature heatpump, the maximum practical condenser operating temperature is about135° C. When HFC-245fa is used as the working fluid in a hightemperature heat pump, the maximum practical condenser operatingtemperature is about 144° C. In one embodiment of the method to raisethe condenser operating temperature, when a composition comprising atleast one alkyl perfluoroalkene ether is used as the heat pump workingfluid, the condenser operating temperature is raised to a temperaturegreater than about 150° C.

In another embodiment of the method to raise the condenser operatingtemperature, when a composition comprising at least one alkylperfluoroalkene ether, is used as the heat pump working fluid, thecondenser operating temperature is raised to a temperature greater thanabout 160° C. In another embodiment of the method to raise the condenseroperating temperature, when a composition comprising at least one alkylperfluoroalkene ether, is used as the heat pump working fluid, thecondenser operating temperature is raised to a temperature greater thanabout 170° C. In another embodiment of the method to raise the condenseroperating temperature, when a composition comprising at least one alkylperfluoroalkene ether, is used as the heat pump working fluid, thecondenser operating temperature is raised to a temperature greater thanabout 180° C. In another embodiment of the method to raise the condenseroperating temperature, when a composition comprising at least one alkylperfluoroalkene ether, is used as the heat pump working fluid, thecondenser operating temperature is raised to a temperature greater thanabout 190° C. In another embodiment of the method to raise the condenseroperating temperature, when a composition comprising at least one alkylperfluoroalkene ether, is used as the heat pump working fluid, thecondenser operating temperature is raised to a temperature greater thanabout 200° C. In another embodiment of the method to raise the condenseroperating temperature, when a composition comprising at least one alkylperfluoroalkene ether, is used as the heat pump working fluid, thecondenser operating temperature is raised to a temperature greater thanabout 210° C. In another embodiment of the method to raise the condenseroperating temperature, when a composition comprising at least one alkylperfluoroalkene ether, is used as the heat pump working fluid, thecondenser operating temperature is raised to a temperature greater thanabout 220° C. In another embodiment of the method to raise the condenseroperating temperature, when a composition comprising at least one alkylperfluoroalkene ether, is used as the heat pump working fluid, thecondenser operating temperature is raised to a temperature greater thanabout 230° C.

It may be feasible that temperatures as high as 230° C. are achievablewith a high temperature heat pump utilizing at least one alkylperfluoroalkene ether as working fluid. However at temperatures above120° C., some modification of compressor, or compressor materials, maybe necessary.

In accordance with this invention it is also possible to use a workingfluid comprising at least one alkyl perfluoroalkene ether in a systemoriginally designed as a chiller using a conventional chiller workingfluid (for example a chiller using HFC-134a or HCFC-123 or HFC-245fa)for the purpose of converting the system to a high temperature heat pumpsystem. For example, a conventional chiller working fluid can bereplaced in an existing chiller system with a working fluid comprisingat least one alkyl perfluoroalkene ether to achieve this purpose.

In accordance with this invention it is also possible to use a workingfluid comprising at least one alkyl perfluoroalkene ether in a systemoriginally designed as a comfort (i.e., low temperature) heat pumpsystem using a conventional comfort heat pump working fluid (for examplea heat pump using HFC-134a or HCFC-123 or HFC-245fa) for the purpose ofconverting the system to a high temperature heat pump system. Forexample, a conventional comfort heat pump working fluid can be replacedin an existing comfort heat pump system with a working fluid comprisingat least one alkyl perfluoroalkene ether to achieve this purpose.

A composition comprising at least one alkyl perfluoroalkene etherenables the design and operation of dynamic (e.g. centrifugal) orpositive displacement (e.g. screw or scroll) heat pumps for upgradingheat available at low temperatures to meet demands for heating at highertemperatures. The available low temperature heat is supplied to theevaporator and the high temperature heat is extracted at the condenser.For example, waste heat can be available to be supplied to theevaporator of a heat pump operating at 100° C. at a location (e.g. anindustrial facility) where heat from the condenser, operating at 140°C., can be used for a drying operation.

In some cases heat may be available from various other sources (e.g.waste heat from process streams, geothermal heat or solar heat) attemperatures higher than suggested above, while heating at even highertemperatures may be required. For example, waste heat or geothermal heatmay be available at 125° C. while heating at 175° C. may be required foran industrial application (e.g. generation of high temperature steam).The lower temperature heat can be supplied to the evaporator of adynamic (e.g. centrifugal) or positive displacement heat pump in themethod or system of this invention to be uplifted to the desiredtemperature of 175° C. and be delivered at the condenser.

High Temperature Heat Pump Apparatus

In one embodiment of the present invention is provided a hightemperature heat pump apparatus containing a working fluid comprising atleast one alkyl perfluoroalkene ether.

In one embodiment of the high temperature heat pump apparatus, theworking fluid comprises at least one alkyl perfluoroalkene etherselected from the group consisting of:

-   -   a) compounds of formula CF₃(CF₂)_(x)CF═CFCF(OR)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)C(OR)═CFCF₂(CF₂)_(y)CF₃,        CF₃CF═CFCF(OR)(CF₂)_(x)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)CF═C(OR)CF₂(CF₂)_(y)CF₃, or mixtures thereof,        wherein R can be either CH₃, C₂H₅ or mixtures thereof, and        wherein x and y are independently 0, 1, 2 or 3, and wherein        x+y=0, 1, 2 or 3 having the formula;    -   b) compounds of formulas CF₃(CF₂)_(x)CF═CFCF(OR)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)C(OR)═CFCF₂(CF₂)_(y)CF₃,        CF₃CF═CFCF(OR)(CF₂)_(x)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)CF═C(OR)CF₂(CF₂)_(y)CF₃, and mixtures thereof;        wherein x and y are independently 0, 1, 2, 3 or 4 and wherein        x+y=0, 1, 2, 3 or 4; and wherein R is        2,2,3,3-tetrafluoro-1-propyl, 2,2,3,3,3-pentafluoro-1-propyl,        2,2,2-trifluoro-1-ethyl, 2,2,3,3,4,4,5,5-octafluoro-1-pentyl, or        1,1,1,3,3,3-hexafluoro-2-propyl; and    -   c) mixtures of compounds from (a) and (b).

In one embodiment of the high temperature heat pump apparatus, the alkylperfluoroalkene ethers comprise at least one of5-methoxyperfluoro-3-heptene, 3-methoxyperfluoro-3-heptene,4-methoxyperfluoro-2-heptene, 3-methoxyperfluoro-2-heptene, or mixturesthereof.

In one embodiment of the high temperature heat pump apparatus, the alkylperfluoroalkene ethers comprise at least one of4-methoxyperfluoro-2-pentene, 2-methoxyperfluoro-2-pentene,3-methoxyperfluoro-2-pentene, 2-methoxyperfluoro-3-pentene, or mixturesthereof.

In one embodiment of the high temperature heat pump apparatus, the alkylperfluoroalkene ethers comprise at least one of cis- andtrans-2-methoxyperfluoro-2-octene, 2-methoxyperfluoro-3-octene, ormixtures thereof.

In one embodiment of the high temperature heat pump apparatus, theworking fluid further comprises at least one compound selected fromhydrofluorocarbons, hydrochlorocarbons, hydrofluoroethers,hydrofluoroolefins, hydrochlorofluorolefins, siloxanes, hydrocarbons,alcohols, perfluoropolyethers, and mixtures thereof.

In one embodiment of the high temperature heat pump apparatus, theworking fluid comprises azeotropic or near-azeotropic mixtures. In oneembodiment, the azeotropic or near azeotropic mixture comprises at leastone methyl perfluoroheptene ether and at least one compound selectedfrom the group consisting of heptane, ethanol, andtrans-1,2-dichloroethene as disclosed in.

In another embodiment, the azeotropic or near azeotropic mixturecomprises at least one methyl perfluoropentene ether and at least onecompound selected from the group consisting of trans-1,2-dichloroethene,methanol, ethanol, 2-propanol, cyclopentane, ethyl formate, methylformate, and 1-bromopropane.

In yet another embodiment of the high temperature heat pump apparatus,the working fluid comprises at least one alkyl perfluoroalkene ether andoptionally one or more fluids selected from the group consisting ofHFC-161, HFC-32, HFC-125, HFC-143a, HFC-245cb, HFC-134a, HFC-134,HFC-227ea, HFC-236ea, HFC-245fa, HFC-245eb, HFC-365mfc, HFC-4310mee,HFO-1234yf, HFO-1234ze-E, HFO-1234ze-Z, HFO-1336mzz-E, HFO-1336mzz-Z,HFO-1234ye-E or Z (1,2,3,3-tetrafluoropropene), HFO-1438mzz-E,HFO-1438mzz-Z, HFO-1438ezy-E, HFO-1438ezy-Z, HFO-1336yf, HFO-1336ze-E,HFO-1336ze-Z, HCFO-1233zd-E, HCFO-1233zd-Z, HCFO-1233xf, HFE-7000 (alsoknown as HFE-347mcc or n-C₃F₇OCH₃), HFE-7100 (also known as HFE-449mcccor C₄F₉OCH₃), HFE-7200 (also known as HFE-569mccc or C₄F₉OC₂H₅),HFE-7500 (also known as3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-trifluoromethyl-hexaneor (CF₃)₂CFCF(OC₂H₅)CF₂CF₂CF₃),1,1,1,2,2,4,5,5,5-nonafluoro-4-(trifluoromethyl)-3-pentanone (sold underthe trademark Novec™ 1230 by 3M, St. Paul, Minn., USA),octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane,octamethyltrisiloxane (OMTS), hexamethyldisiloxane (HMDS), n-pentane,isopentane, cyclopentane, hexanes, cyclohexane, heptanes, and toluene.

A heat pump is a type of apparatus for producing heating and/or cooling.A heat pump includes an evaporator, a compressor, a condenser orsupercritical working fluid cooler, and an expansion device. A workingfluid circulates through these components in a repeating cycle. Heatingis produced at the condenser where energy (in the form of heat) isextracted from the vapor working fluid as it is condensed to form liquidworking fluid. Cooling is produced at the evaporator where energy isabsorbed to evaporate the working fluid to form vapor working fluid.

In one embodiment, the high temperature heat pump apparatus of thepresent invention comprises (a) an evaporator through which a workingfluid flows and is evaporated; (b) a compressor in fluid communicationwith the evaporator that compresses the evaporated working fluid to ahigher pressure; (c) a condenser in fluid communication with thecompressor through which the high pressure working fluid vapor flows andis condensed; and (d) a pressure reduction device in fluid communicationwith the condenser wherein the pressure of the condensed working fluidis reduced and said pressure reduction device further being in fluidcommunication with the evaporator such that the working fluid thenrepeats flow through components (a), (b), (c) and (d) in a repeatingcycle.

In one embodiment, the high temperature heat pump apparatus uses aworking fluid comprising at least one alkyl perfluoroalkene ether. Ofnote are working fluids that consist essentially of at least one alkylperfluoroalkene ether.

Of particular utility in the high temperature heat pump apparatus arethose embodiments wherein the working fluid consists essentially of atleast one alkyl perfluoroalkene ether. Also of particular utility arethose embodiments wherein the working fluid comprises an azeotropic ornear azeotropic composition.

Also of particular utility in the high temperature heat pump apparatusare those embodiments wherein the working fluid has a low GWP.

Heat pumps may include flooded evaporators one embodiment of which isshown in FIG. 1, or direct expansion evaporators one embodiment of whichis shown in FIG. 2.

Heat pumps may utilize positive displacement compressors or centrifugalcompressors. Positive displacement compressors include reciprocating,screw, or scroll compressors. Of note are heat pumps that use screwcompressors. Also of note are heat pumps that use centrifugalcompressors.

Residential heat pumps are used to produce heated air to warm aresidence or home (including single family or multi-unit attached homes)and produce maximum condenser operating temperatures from about 30° C.to about 50° C.

Of note are high temperature heat pumps that may be used to heat air,water, another heat transfer medium or some portion of an industrialprocess, such as a piece of equipment, storage area or process stream.In one embodiment, high temperature heat pumps can produce condenseroperating temperatures greater than about 55° C. In another embodiment,high temperature heat pumps can produce condenser operating temperaturesgreater than about 75° C. In another embodiment, high temperature heatpumps can produce condenser operating temperatures greater than about100° C. In another embodiment, high temperature heat pumps can producecondenser operating temperatures greater than about 120° C. The maximumcondenser operating temperature that can be achieved in a hightemperature heat pump will depend upon the working fluid used. Thismaximum condenser operating temperature is limited by the normal boilingcharacteristics of the working fluid and also by the pressure to whichthe heat pump's compressor can raise the vapor working fluid pressure.This maximum pressure is also related to the working fluid used in theheat pump.

In some embodiments, high temperature heat pumps can operate atcondenser temperatures greater than about 55° C. In another embodiment,high temperature heat pumps can operate at condenser temperaturesgreater than about 60° C. In another embodiment, high temperature heatpumps can operate at condenser temperatures greater than about 65° C. Inanother embodiment, high temperature heat pumps can operate at condensertemperatures greater than about 75° C. In another embodiment, the hightemperature heat pump operates at condenser temperatures greater thanabout 100° C. In another embodiment, high temperature heat pumps canproduce condenser operating temperatures greater than about 120° C.

Of particular value are high temperature heat pumps that operate atcondenser temperatures of 150° C. or higher. Alkyl perfluoroalkeneethers enable the design and operation of centrifugal heat pumps,operated at condenser temperatures higher than those accessible withmany currently available working fluids. A working fluid comprising atleast one alkyl perfluoroalkene ether may enable the design andoperation of heat pumps, operated at condenser temperatures higher thanthose accessible with many currently available working fluids.

Also of note are heat pumps that are used to produce heating and coolingsimultaneously. For instance, a single heat pump unit may produceheating to be used to generate high temperature steam for industrial useand may also produce cooling to be used to cool an industrial processstream.

Heat pumps, including both flooded evaporator and direct expansion, maybe coupled with an air handling and distribution system to providedrying and dehumidification. In another embodiment, heat pumps may beused to heat water or generate steam.

To illustrate how heat pumps operate, reference is made to the Figures.A flooded evaporator heat pump is shown in FIG. 1.

In this heat pump a second heat transfer medium, which in someembodiments is a warm liquid, which may comprise water, and, in someembodiments, additives, or other heat transfer medium such as a glycol(e.g., ethylene glycol or propylene glycol), enters the heat pumpcarrying heat from a low temperature source (not shown), such as forinstance, an industrial vessel or process stream, shown entering theheat pump at arrow 3, through a tube bundle or coil 9, in an evaporator6, which has an inlet and an outlet. The warm second heat transfermedium is delivered to evaporator 6, where it is cooled by liquidworking fluid, which is shown in the lower portion of evaporator 6. Theliquid working fluid evaporates at a lower temperature than the warmfirst heat transfer medium which flows through tube bundle or coil 9.The cooled second heat transfer medium re-circulates back to the lowtemperature heat source as shown by arrow 4, via a return portion oftube bundle or coil 9. The liquid working fluid, shown in the lowerportion of evaporator 6 in FIG. 1, vaporizes and is drawn intocompressor 7, which increases the pressure and temperature of theworking fluid vapor. Compressor 7 compresses this vapor so that it maybe condensed in condenser 5 at a higher pressure and temperature thanthe pressure and temperature of the working fluid vapor when it exitsevaporator 6. A first heat transfer medium enters the condenser via atube bundle or coil 10 in condenser 5 from a location where hightemperature heat is provided (“heat sink”) such as a service waterheater or a steam generation system at arrow 1 in FIG. 1. The first heattransfer medium is warmed in the process and returned via a return loopof tube bundle or coil 10 and arrow 2 to the heat sink. This first heattransfer medium cools the working fluid vapor in condenser 5 and causesthe vapor to condense to liquid working fluid, so that there is liquidworking fluid in the lower portion of condenser 5 as shown in FIG. 1.Condensed liquid working fluid in condenser 5 flows back to evaporator 6through expansion device 8, which may be an orifice, capillary tube orexpansion valve. Expansion device 8 reduces the pressure of the liquidworking fluid, and converts the liquid working fluid at least partiallyto vapor, that is to say that the liquid working fluid flashes aspressure drops between condenser 5 and evaporator 6. Flashing cools theworking fluid, i.e., both the liquid working fluid and the working fluidvapor to the saturated temperature at evaporator pressure, so that bothliquid working fluid and working fluid vapor are present in evaporator6.

In some embodiments the working fluid vapor is compressed to asupercritical state and condenser 5 is replaced by a gas cooler wherethe working fluid vapor is cooled to a liquid state withoutcondensation.

In some embodiments the second heat transfer medium used in theapparatus depicted in FIG. 1 is a medium returning from a location wherecooling is provided to a stream or a body to be cooled. Heat isextracted from the returning second heat transfer medium at theevaporator 6 and the cooled second heat transfer medium is supplied backto the location or body to be cooled. In this embodiment the apparatusdepicted in FIG. 1 functions to simultaneously cool the second heattransfer medium that provides cooling to a body to be cooled (e.g. aprocess stream) and heat the first heat transfer medium that providesheating to a body to be heated (e.g. service water or steam or a processstream).

It is understood that the apparatus depicted in FIG. 1 can extract heatat the evaporator 6 from a wide variety of heat sources including solar,geothermal and waste heat and supply heat from the condenser 5 to a widerange of heat sinks.

It should be noted that for a single component working fluidcomposition, the composition of the vapor working fluid in theevaporator and condenser is the same as the composition of the liquidworking fluid in the evaporator and condenser. In this case, evaporationwill occur at a constant temperature. However, if a working fluid blend(or mixture) is used, as in the present invention, the liquid workingfluid and the working fluid vapor in the evaporator (or in thecondenser) may have different compositions. This may lead to inefficientsystems and difficulties in servicing the equipment. An azeotrope orazeotrope-like composition will function essentially as a singlecomponent working fluid in a heat pump, such that the liquid compositionand the vapor composition are essentially the same reducing anyinefficiencies that might arise from the use of a non-azeotropic ornon-azeotrope-like composition. The above discussion notwithstanding, insome embodiments zeotropic working fluids may be advantageous increating condenser and/or evaporator temperature glides that largelymatch the temperature variations in the heat sink and/or heat source,respectively, so as to increase the effectiveness of heat exchangebetween the working fluid and the sink and/or source.

One embodiment of a direct expansion heat pump is illustrated in FIG. 2.In the heat pump as illustrated in FIG. 2, liquid second heat transfermedium, which in some embodiments is a warm liquid, such as warm water,enters evaporator 6′ at inlet 14. Mostly liquid working fluid (with asmall amount of working fluid vapor) enters coil 9′ in the evaporator atarrow 3′ and evaporates. As a result, second liquid heat transfer mediumis cooled in evaporator 6′, and a cooled second liquid heat transfermedium exits evaporator 6′ at outlet 16, and is sent to low temperatureheat source (e.g. warm water flowing to a cooling tower). The workingfluid vapor exits evaporator 6′ at arrow 4′ and is sent to compressor7′, where it is compressed and exits as high temperature, high pressureworking fluid vapor. This working fluid vapor enters condenser 5′through condenser coil 10′ at 1′. The working fluid vapor is cooled by aliquid first heat transfer medium, such as water, in condenser 5′ andbecomes a liquid. The liquid first heat transfer medium enters condenser5′ through condenser heat transfer medium inlet 20. The liquid firstheat transfer medium extracts heat from the condensing working fluidvapor, which becomes liquid working fluid, and this warms the liquidfirst heat transfer medium in condenser 5′. The liquid first heattransfer medium exits from condenser 5′ through condenser heat transfermedium outlet 18. The condensed working fluid exits condenser 5′ throughlower coil or tube bundle 10′ as shown in FIG. 2 and flows throughexpansion device 12, which may be an orifice, capillary tube orexpansion valve. Expansion device 12 reduces the pressure of the liquidworking fluid. A small amount of vapor, produced as a result of theexpansion, enters evaporator 6′ with liquid working fluid through coil9′ and the cycle repeats.

In some embodiments the working fluid vapor is compressed to asupercritical state and vessel 5′ in FIG. 2 represents a gas coolerwhere the working fluid vapor is cooled to a liquid state withoutcondensation.

In some embodiments the first liquid heating medium used in theapparatus depicted in FIG. 2 is a medium returning from a location wherecooling is provided to a stream or a body to be cooled. Heat isextracted from the returning second heat transfer medium at theevaporator 6′ and the cooled second heat transfer medium is suppliedback to the location or body to be cooled. In this embodiment theapparatus depicted in FIG. 2 functions to simultaneously cool the secondheat transfer medium (may be referred to as a liquid heating mediumsince it provides heating to the working fluid) that provides cooling toa body to be cooled (e.g. a process stream) and heat the first heattransfer medium (or liquid heating medium) that provides heating to abody to be heated (e.g. service water or process stream).

It is understood that the apparatus depicted in FIG. 2 can extract heatat the evaporator 6′ from a wide variety of heat sources includingsolar, geothermal and waste heat and supply heat from the condenser 5′to a wide range of heat sinks.

Compressors useful in the present invention include dynamic compressors.Of note as examples of dynamic compressors are centrifugal compressors.A centrifugal compressor uses rotating elements to accelerate theworking fluid radially, and typically includes an impeller and diffuserhoused in a casing. Centrifugal compressors usually take working fluidin at an impeller eye, or central inlet of a circulating impeller, andaccelerate it radially outward. Some static pressure rise occurs in theimpeller, but most of the pressure rise occurs in the diffuser sectionof the casing, where velocity is converted to static pressure. Eachimpeller-diffuser set is a stage of the compressor. Centrifugalcompressors are built with from 1 to 12 or more stages, depending on thefinal pressure desired and the volume of refrigerant to be handled.

The pressure ratio, or compression ratio, of a compressor is the ratioof absolute discharge pressure to the absolute inlet pressure. Pressuredelivered by a centrifugal compressor is practically constant over arelatively wide range of capacities. The pressure a centrifugalcompressor can develop depends on the tip speed of the impeller. Tipspeed is the speed of the impeller measured at its tip and is related tothe diameter of the impeller and its revolutions per minute The tipspeed required in a specific application depends on the compressor workthat is required to elevate the thermodynamic state of the working fluidfrom evaporator to condenser conditions. The volumetric flow capacity ofthe centrifugal compressor is determined by the size of the passagesthrough the impeller. This makes the size of the compressor moredependent on the pressure required than the volumetric flow capacityrequired.

Also of note as examples of dynamic compressors are axial compressors. Acompressor in which the fluid enters and leaves in the axial directionis called an axial flow compressor. Axial compressors are rotating,airfoil- or blade-based compressors in which the working fluidprincipally flows parallel to the axis of rotation. This is in contrastwith other rotating compressors such as centrifugal or mixed-flowcompressors where the working fluid may enter axially but will have asignificant radial component on exit. Axial flow compressors produce acontinuous flow of compressed gas, and have the benefits of highefficiencies and large mass flow capacity, particularly in relation totheir cross-section. They do, however, require several rows of airfoilsto achieve large pressure rises making them complex and expensiverelative to other designs.

Compressors useful in the present invention also include positivedisplacement compressors. Positive displacement compressors draw vaporinto a chamber, and the chamber decreases in volume to compress thevapor. After being compressed, the vapor is forced from the chamber byfurther decreasing the volume of the chamber to zero or nearly zero.

Of note as examples of positive displacement compressors arereciprocating compressors. Reciprocating compressors use pistons drivenby a crankshaft. They can be either stationary or portable, can besingle or multi-staged, and can be driven by electric motors or internalcombustion engines. Small reciprocating compressors from 5 to 30 hp areseen in automotive applications and are typically for intermittent duty.Larger reciprocating compressors up to 100 hp are found in largeindustrial applications. Discharge pressures can range from low pressureto very high pressure (above 5000 psi or 35 MPa).

Also of note as examples of positive displacement compressors are screwcompressors. Screw compressors use two meshed rotatingpositive-displacement helical screws to force the gas into a smallerspace. Screw compressors are usually for continuous operation incommercial and industrial application and may be either stationary orportable. Their application can be from 5 hp (3.7 kW) to over 500 hp(375 kW) and from low pressure to very high pressure (above 1200 psi or8.3 MPa).

Also of note as examples of positive displacement compressors are scrollcompressors. Scroll compressors are similar to screw compressors andinclude two interleaved spiral-shaped scrolls to compress the gas. Theoutput is more pulsed than that of a rotary screw compressor.

In one embodiment, the high temperature heat pump apparatus may comprisemore than one heating circuit (or loop or stage) in a cascadearrangement. The performance (coefficient of performance for heating andvolumetric heating capacity) of high temperature heat pumps operatedwith at least one alkyl perfluoroalkene ether as the working fluid isdrastically improved when the evaporator is operated at temperaturesapproaching the condenser temperature required by the application. Whenthe heat supplied to the evaporator is only available at lowtemperatures, thus requiring high temperature lifts leading to poorperformance, a cascade cycle configuration with multiple circuits (orloops or stages) will be advantageous. The working fluid used in eachcascade circuit (or loop or stage) is selected to have optimumthermodynamic and chemical stability properties for the temperaturerange encountered in the cascade circuit or stage in which the fluid isused.

In one embodiment of a cascade heat pump, the heat pump has two circuitsor stages. In one embodiment, the low stage or low temperature circuitof the cascade cycle with two circuits or stages may be operated with aworking fluid of lower boiling point than the boiling point of theworking fluid used in the upper or high stage. In one embodiment, thehigh stage or high temperature circuit of the cascade cycle may beoperated with a working fluid comprising at least one alkylperfluoroalkene ether and optionally one or more compounds selected fromhydrofluorocarbons, hydrochlorocarbons, hydrofluoroethers,hydrofluoroolefins, hydrochlorofluorolefins, siloxanes, hydrocarbons,alcohols, perfluoropolyethers, and mixtures thereof and preferably witha low GWP. In another embodiment, the low stage or low temperaturecircuit of the cascade cycle may be operated with a working fluidcomprising at least one compound selected from alkyl perfluoroalkeneethers, hydrofluorocarbons, hydrochlorocarbons, hydrofluoroethers,hydrofluoroolefins, hydrochlorofluorolefins, siloxanes, hydrocarbons,alcohols, perfluoropolyethers, and mixtures thereof boiling attemperatures lower than the working fluid of the upper or higher stageand preferably with a low GWP. In one embodiment, the low stage or lowtemperature circuit of the cascade cycle would be operated with aworking fluid comprising at least one compound selected from HFC-161,HFC-32, HFC-125, HFC-143a, HFC-245cb, HFC-134a, HFC-134, HFC-227ea,HFC-236ea, HFC-245fa, HFC-245eb, HFC-365mfc, HFC-4310mee, HFO-1234yf,HFO-1234ze-E, HFO-1234ze-Z, HFO-1336mzz-E, HFO-1336mzz-Z, HFO-1234ye-Eor Z (1,2,3,3-tetrafluoropropene), HFO-1438mzz-E, HFO-1438mzz-Z,HFO-1438ezy-E, HFO-1438ezy-Z, HFO-1336yf, HFO-1336ze-E, HFO-1336ze-Z,HCFO-1233zd-E, HCFO-1233zd-Z, HCFO-1233xf, HFE-7000 (also known asHFE-347mcc or n-C₃F₇OCH₃), HFE-7100 (also known as HFE-449mccc orC₄F₉OCH₃), HFE-7200 (also known as HFE-569mccc or C₄F₉OC₂H₅), HFE-7500(also known as3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-trifluoromethyl-hexaneor (CF₃)₂CFCF(OC₂H₅)CF₂CF₂CF₃),1,1,1,2,2,4,5,5,5-nonafluoro-4-(trifluoromethyl)-3-pentanone (sold underthe trademark Novec™ 1230 by 3M, St. Paul, Minn., USA),octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane,octamethyltrisiloxane (OMTS), hexamethyldisiloxane (HMDS), n-pentane,isopentane, cyclopentane, hexanes, cyclohexane, heptanes, and toluene.Also of particular utility in the method for producing heating are thoseembodiments wherein the working fluids have low GWP.

In another embodiment of a cascade heat pump, the heat pump has threecircuits or stages. When the heat supplied to the evaporator is onlyavailable at even lower temperatures than in the previous example, thusrequiring high temperature lifts leading to poor performance, a cascadecycle configuration with three stages or three circuits will beadvantageous. In one embodiment, the lowest stage or lowest temperaturecircuit of the cascade cycle may be operated with a working fluid oflower boiling point than the boiling point of the working fluid used inthe second or intermediate stage. In one embodiment, the high stage orhigh temperature circuit of the cascade cycle may be operated with aworking fluid comprising at least one alkyl perfluoroalkene ether andoptionally one or more compounds selected from hydrofluorocarbons,hydrochlorocarbons, hydrofluoroethers, hydrofluoroolefins,hydrochlorofluorolefins, siloxanes, hydrocarbons, alcohols,perfluoropolyethers, and mixtures thereof and preferably with a low GWP.In one embodiment, the intermediate stage or intermediate temperaturecircuit of the cascade cycle may be operated with a working fluidcomprising at least one compound selected from alkyl perfluoroalkeneethers, hydrofluorocarbons, hydrochlorocarbons, hydrofluoroethers,hydrofluoroolefins, hydrochlorofluorolefins, siloxanes, hydrocarbons,alcohols, perfluoropolyethers, and mixtures thereof and preferably witha low GWP. In one embodiment, the low stage or low temperature circuitof the cascade cycle would be operated with a working fluid comprisingat least one compound selected from alkyl perfluoroalkene ethers,hydrofluorocarbons, hydrochlorocarbons, hydrofluoroethers,hydrofluoroolefins, hydrochlorofluorolefins, siloxanes, hydrocarbons,alcohols, perfluoropolyethers, and mixtures thereof and preferably witha low GWP. In another embodiment, the low stage or low temperaturecircuit of the cascade cycle may be operated with a working fluidcomprising at least one compound selected from HFC-161, HFC-32(difluoromethane), HFC-125 (pentafluoroethane), HFC-143a(1,1,1-trifluoroethane), HFC-152a (1,1-difluoroethane), HFC-245cb,HFC-134a (1,1,1,2-tetrafluoroethane), HFC-134(1,1,2,2-tetrafluoroethane), HFC-227ea(1,1,1,2,3,3,3-heptafluoropropene), HFC-236ea, HFC-245fa, HFC-245eb,HFC-365mfc, HFC-4310mee, HFO-1234yf, HFO-1234ze-E, HFO-1243zf(3,3,3-trifluoropropene), HFO-1234ze-Z, HFO-1336mzz-E, HFO-1234ye-E or Z(1,2,3,3-tetrafluoropropene), HFO-1336mzz-Z, HFO-1438mzz-E,HFO-1438mzz-Z, HFO-1438ezy-E, HFO-1438ezy-Z, HFO-1336yf, HFO-1336ze-E,HFO-1336ze-Z, HCFO-1233zd-E, HCFO-1233zd-Z, HCFO-1233xf, HFE-7000 (alsoknown as HFE-347mcc or n-C₃F₇OCH₃), HFE-7100 (also known as HFE-449mcccor C₄F₉OCH₃), HFE-7200 (also known as HFE-569mccc or C₄F₉OC₂H₅),HFE-7500 (also known as3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-trifluoromethyl-hexaneor (CF₃)₂CFCF(OC₂H₅)CF₂CF₂CF₃),1,1,1,2,2,4,5,5,5-nonafluoro-4-(trifluoromethyl)-3-pentanone (sold underthe trademark Novec™ 1230 by 3M, St. Paul, Minn., USA),octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane,octamethyltrisiloxane (OMTS), hexamethyldisiloxane (HMDS), n-pentane,isopentane, cyclopentane, hexanes, cyclohexane, heptanes, and toluene.

In one embodiment, the low stage or low temperature circuit of thethree-stage cascade cycle may be operated with a working fluidcomprising at least one compound selected from HFC-161, HFC-32(difluoromethane), HFC-125 (pentafluoroethane), HFC-143a(1,1,1-trifluoroethane), HFC-152a (1,1-difluoroethane), HFC-245cb,HFC-134a (1,1,1,2-tetrafluoroethane), HFC-134(1,1,2,2-tetrafluoroethane), HFC-227ea(1,1,1,2,3,3,3-heptafluoropropene), HFO-1234yf, HFO-1234ze-E, HFO-1243zf(3,3,3-trifluoropropene). Of note are working fluids for the low stageof a three-stage cascade heat pump such as HFO-1234yf/HFC-32,HFO-1234yf/HFC-32/HFC-125, HFO-1234yf/HFC-134a,HFO-1234yf/HFC-134a/HFC-32, HFO-1234yf/HFC-134,HFO-1234yf/HFC-134a/HFC-134, HFO-1234yf/HFC-32/HFC-125/HFC-134a,E-HFO-1234ze/HFC-32, E-HFO-1234ze/HFC-32/HFC-125, E-HFO-1234ze/HFC-134a,E-HFO-1234ze/HFC-134, E-HFO-1234ze/HFC-134a/HFC-134,E-HFO-1234ze/HFC-227ea, E-HFO-1234ze/HFC-134/HFC-227ea,E-HFO-1234ze/HFC-134/HFC-134a/HFC-227ea,HFO-1234yf/E-HFO-1234ze/HFC-134/HFC-134a/HFC-227ea, etc. Also ofparticular utility in the method for producing heating are thoseembodiments wherein the working fluids have low GWPs.

The evaporator of the low temperature circuit (or low temperature loop)of the two-stage cascade cycle receives the available low temperatureheat, lifts the heat to a temperature intermediate between thetemperature of the available low temperature heat and the temperature ofthe required heating duty and transfers the heat to the high stage orhigh temperature circuit (or high temperature loop) of the cascadesystem at a cascade heat exchanger. Then the high temperature circuit,operated with a working fluid comprising at least one alkylperfluoroalkene ether, further lifts the heat received at the cascadeheat exchanger to the required condenser temperature to meet theintended heating duty. The cascade concept can be extended toconfigurations with three or more circuits lifting heat over widertemperature ranges and using different fluids over different temperaturesub-ranges to optimize performance.

In one embodiment of the high temperature heat pump apparatus havingmore than one stage, the working fluid used in the lowest temperaturestage comprises at least one fluoroolefin selected from the groupconsisting of HFO-1234yf, E-HFO-1234ze, HFO-1234ye (E- or Z-isomer),HFO-1336mzz-E, and HFC-1243zf.

In another embodiment of the high temperature heat pump apparatus havingmore than one stage, the working fluid used in the lowest temperaturestage comprises at least one fluoroalkane selected from the groupconsisting of HFC-161, HFC-32, HFC-125, HFC-245cb, HFC-134a, HFC-134,HFC-143a, HFC-152a and HFC-227ea.

In another embodiment of the high temperature heat pump apparatus havingmore than one stage, the working fluid of the stage preceding the finalor highest-temperature stage comprises at least one fluoroolefin orchlorofluorolefin selected from the group consisting of HFO-1234yf,HFO-1234ze-E, HFO-1243zf (3,3,3-trifluoropropene), HFO-1234ze-Z,HFO-1336mzz-E, HFO-1234ye-E or Z (1,2,3,3-tetrafluoropropene, E- orZ-isomer), HFO-1336mzz-Z, HFO-1438mzz-E, HFO-1438mzz-Z, HFO-1438ezy-E,HFO-1438ezy-Z, HFO-1336yf, HFO-1336ze-E, HFO-1336ze-Z, HCFO-1233zd-E,HCFO-1233zd-Z, HCFO-1233xf.

In another embodiment of the high temperature heat pump apparatus havingmore than one stage, wherein the working fluid of the stage precedingthe final or highest-temperature stage comprises at least onefluoroalkane selected from the group consisting of HFC-161, HFC-32,HFC-125, HFC-245cb, HFC-134a, HFC-134, HFC-143a, HFC-152a and HFC-227ea,HFC-236ea, HFC-245fa, HFC-245eb, HFC-365mfc, HFC-4310mee.

In accordance with the present invention, there is provided a cascadeheat pump system having at least two heating loops for circulating aworking fluid through each loop. In one embodiment, the high temperatureheat pump apparatus has at least two heating stages arranged as acascade heating system, wherein each stage is in thermal communicationwith the next stage and wherein each stage circulates a working fluidtherethrough, wherein heat is transferred to the final or upper orhighest-temperature stage from the immediately preceding stage andwherein the heating fluid of the final stage comprises at least onealkyl perfluoroalkene ether.

In another embodiment the high temperature heat pump apparatus has atleast two heating stages arranged as a cascade heating system, eachstage circulating a working fluid therethrough comprising (a) a firstexpansion device for reducing the pressure and temperature of a firstworking fluid liquid; (b) an evaporator in fluid communication with thefirst expansion device having an inlet and an outlet; (c) a firstcompressor in fluid communication with the evaporator and having aninlet and an outlet; (d) a cascade heat exchanger system in fluidcommunication with the first compressor and having: (i) a first inletand a first outlet, and (ii) a second inlet and a second outlet inthermal communication with the first inlet and outlet; (e) a secondcompressor in fluid communication with the second outlet of the cascadeheat exchanger and having an inlet and an outlet; (f) a condenser influid communication with the second compressor and having an inlet andan outlet; and (g) a second expansion device in fluid communication withthe condenser; wherein the second working fluids comprises at least onealkyl perfluoroalkene ether. In accordance with the present invention,there is provided a cascade heat pump system having at least two heatingloops for circulating a working fluid through each loop. One embodimentof such a cascade system is shown generally at 110 in FIG. 3. Cascadeheat pump system 110 of the present invention has at least two heatingloops, including a first, or lower loop 112, which is a low temperatureloop, and a second, or upper loop 114, which is a high temperature loop114 as shown in FIG. 3. Each circulates a working fluid therethrough.

Cascade heat pump system 110 includes first expansion device 116. Firstexpansion device 116 has an inlet 116 a and an outlet 116 b. Firstexpansion device 116 reduces the pressure and temperature of a firstworking fluid liquid which circulates through the first or lowtemperature loop 112.

Cascade heat pump system 110 also includes evaporator 118. Evaporator118 has an inlet 118 a and an outlet 118 b. The first working fluidliquid from first expansion device 116 enters evaporator 118 throughevaporator inlet 118 a and is evaporated in evaporator 118 to form afirst working fluid vapor. The first working fluid vapor then circulatesto evaporator outlet 118 b.

Cascade heat pump system 110 also includes first compressor 120. Firstcompressor 120 has an inlet 120 a and an outlet 120 b. The first workingfluid vapor from evaporator 118 circulates to inlet 120 a of firstcompressor 120 and is compressed, thereby increasing the pressure andthe temperature of the first working fluid vapor. The compressed firstworking fluid vapor then circulates to the outlet 120 b of the firstcompressor 120.

Cascade heat pump system 110 also includes cascade heat exchanger system122. Cascade heat exchanger 122 has a first inlet 122 a and a firstoutlet 122 b. The first working fluid vapor from first compressor 120enters first inlet 122 a of heat exchanger 122 and is condensed in heatexchanger 122 to form a first working fluid liquid, thereby rejectingheat. The first working fluid liquid then circulates to first outlet 122b of heat exchanger 122. Heat exchanger 122 also includes a second inlet122 c and a second outlet 122 d. A second working fluid liquidcirculates from second inlet 122 c to second outlet 122 d of heatexchanger 122 and is evaporated to form a second working fluid vapor,thereby absorbing the heat rejected by the first working fluid (as it iscondensed). The second working fluid vapor then circulates to secondoutlet 122 d of heat exchanger 122. Thus, in the embodiment of FIG. 3,the heat rejected by the first working fluid is directly absorbed by thesecond working fluid.

Cascade heat pump system 110 also includes second compressor 124. Secondcompressor 124 has an inlet 124 a and an outlet 124 b. The secondworking fluid vapor from cascade heat exchanger 122 is drawn intocompressor 124 through inlet 124 a and is compressed, thereby increasingthe pressure and temperature of the second working fluid vapor. Thesecond working fluid vapor then circulates to outlet 124 b of secondcompressor 124.

Cascade heat pump system 110 also includes condenser 126 having an inlet126 a and an outlet 126 b. The second working fluid from secondcompressor 124 circulates from inlet 126 a and is condensed in condenser126 to form a second working fluid liquid, thus producing heat. Thesecond working fluid liquid exits condenser 126 through outlet 126 b.

Cascade heat pump system 110 also includes second expansion device 128having an inlet 128 a and an outlet 128 b. The second working fluidliquid passes through second expansion device 128, which reduces thepressure and temperature of the second working fluid liquid exitingcondenser 126. This liquid may be partially vaporized during thisexpansion. The reduced pressure and temperature second working fluidliquid circulates to second inlet 122 c of cascade heat exchanger system122 from expansion device 128.

Moreover, the stability of alkyl perfluoroalkene ethers at temperatureshigher than their critical temperatures enables the design of heat pumpsoperated according to a supercritical or transcritical cycle in whichheat is rejected by the working fluid in a supercritical state and madeavailable for use over a range of temperatures (including temperatureshigher than the critical temperature of the alkyl perfluoroalkeneethers). The supercritical fluid is cooled to a liquid state withoutpassing through an isothermal condensation transition.

For high temperature condenser operation (associated with hightemperature lifts and high compressor discharge temperatures)formulations of working fluid (e.g. methyl perfluoroheptene ethers) andlubricants with high thermal stability (possibly in combination with oilcooling or other mitigation approaches such as fluid injection duringthe compression stage) will be advantageous.

For high temperature condenser operation (associated with hightemperature lifts and high compressor discharge temperatures) the use ofmagnetic centrifugal compressors (e.g., Danfoss-Turbocor type) that donot require the use of lubricants will be advantageous.

For high temperature condenser operation (associated with hightemperature lifts and high compressor discharge temperatures) the use ofcompressor materials (e.g. shaft seals, etc) with high thermal stabilitymay also be required.

The compositions comprising at least one alkyl perfluoroalkene ether maybe used in a high temperature heat pump apparatus in combination withmolecular sieves to aid in removal of moisture. Desiccants may becomposed of activated alumina, silica gel, or zeolite-based molecularsieves. In some embodiments, the molecular sieves are most useful with apore size of approximately 3 Angstroms to 6 Angstroms. Representativemolecular sieves include MOLSIV XH-7, XH-6, XH-9 and XH-11 (UOP LLC, DesPlaines, Ill.).

High Temperature Heat Pump Compositions

A composition is provided for use in high temperature heat pumps. Thecomposition comprises (i) a working fluid consisting essentially of atleast one alkyl perfluoroalkene ether; and (ii) a stabilizer to preventdegradation at temperatures of 55° C. or above; or (iii) a lubricantsuitable for use at 55° C. or above, or both (ii) and (iii). Of note arecompositions wherein the working fluid component consists essentially ofat least one alkyl perfluoroalkene ether or wherein the working fluidcomponent consists of at least one alkyl perfluoroalkene ether.

In one embodiment of the composition for use in high temperature heatpumps, the working fluid comprises at least one alkyl perfluoroalkeneether selected from the group consisting of:

-   -   a) compounds of formula CF₃(CF₂)_(x)CF═CFCF(OR)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)C(OR)═CFCF₂(CF₂)_(y)CF₃,        CF₃CF═CFCF(OR)(CF₂)_(x)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)CF═C(OR)CF₂(CF₂)_(y)CF₃, or mixtures thereof,        wherein R can be either CH₃, C₂H₅ or mixtures thereof, and        wherein x and y are independently 0, 1, 2 or 3, and wherein        x+y=0, 1, 2 or 3 having the formula;    -   b) compounds of formulas CF₃(CF₂)_(x)CF═CFCF(OR)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)C(OR)═CFCF₂(CF₂)_(y)CF₃,        CF₃CF═CFCF(OR)(CF₂)_(x)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)CF═C(OR)CF₂(CF₂)_(y)CF₃, and mixtures thereof;        wherein x and y are independently 0, 1, 2, 3 or 4 and wherein        x+y=0, 1, 2, 3 or 4; and wherein R is        2,2,3,3-tetrafluoro-1-propyl, 2,2,3,3,3-pentafluoro-1-propyl,        2,2,2-trifluoro-1-ethyl, 2,2,3,3,4,4,5,5-octafluoro-1-pentyl, or        1,1,1,3,3,3-hexafluoro-2-propyl; and    -   c) mixtures of compounds from (a) and (b).

In one embodiment of the composition for use in high temperature heatpumps, the alkyl perfluoroalkene ethers comprise at least one of5-methoxyperfluoro-3-heptene, 3-methoxyperfluoro-3-heptene,4-methoxyperfluoro-2-heptene, 3-methoxyperfluoro-2-heptene, or mixturesthereof.

In one embodiment of the composition for use in high temperature heatpumps, the alkyl perfluoroalkene ethers comprise at least one of4-methoxyperfluoro-2-pentene, 2-methoxyperfluoro-2-pentene,3-methoxyperfluoro-2-pentene, 2-methoxyperfluoro-3-pentene, or mixturesthereof.

In one embodiment of the composition for use in high temperature heatpumps, the alkyl perfluoroalkene ethers comprise at least one of cis-and trans-2-methoxyperfluoro-2-octene, 2-methoxyperfluoro-3-octene, ormixtures thereof.

In one embodiment of the composition for use in high temperature heatpumps, the working fluid further comprises at least one compoundselected from hydrofluorocarbons, hydrochlorocarbons, hydrofluoroethers,hydrofluoroolefins, hydrochlorofluorolefins, siloxanes, hydrocarbons,alcohols, perfluoropolyethers, and mixtures thereof.

In one embodiment of the composition for use in high temperature heatpumps, the working fluid comprises azeotropic or near-azeotropicmixtures. In one embodiment, the azeotropic or near azeotropic mixturecomprises at least one methyl perfluoroheptene ether and at least onecompound selected from the group consisting of heptane, ethanol,trans-1,2-dichloroethene, and mixtures thereof.

In another embodiment composition for use in high temperature heatpumps, the azeotropic or near azeotropic mixture comprises at least onemethyl perfluoropentene ether and at least one compound selected fromthe group consisting of trans-1,2-dichloroethene, methanol, ethanol,2-propanol, cyclopentane, ethyl formate, methyl formate, 1-bromopropane,and mixtures thereof.

Of note for use in high temperature heat pumps are working fluids thatare azeotropic or azeotrope-like mixtures. Mixtures that are notazeotropic or azeotrope-like fractionate to some degree while in use ina high temperature heat pump.

In one embodiment of the composition for use in high temperature heatpumps, the working fluid comprises azeotropic or near-azeotropicmixtures. In one embodiment, the azeotropic or near azeotropic mixturecomprises at least one methyl perfluoroheptene ether and at least onecompound selected from the group consisting of heptane, ethanol,trans-1,2-dichloroethene, and mixtures thereof.

In another embodiment composition for use in high temperature heatpumps, the azeotropic or near azeotropic mixture comprises at least onemethyl perfluoropentene ether and at least one compound selected fromthe group consisting of trans-1,2-dichloroethene, methanol, ethanol,2-propanol, cyclopentane, ethyl formate, methyl formate, 1-bromopropane,and mixtures thereof.

Any of the compositions described herein can be used in a hightemperature heat pump. Of note are compositions comprising at least onealkyl perfluoroalkene ether that are particularly useful in hightemperature heat pumps, which are azeotropic or azeotrope-like.Azeotropic compositions will have zero glide in the heat exchangers,e.g., evaporator and condenser, of a high temperature heat pump.

It has been disclosed that at least one alkyl perfluoroalkene ethersform azeotropic and azeotrope-like compositions. In particular,azeotropic and near azeotropic blends of methyl perfluoroheptene etherswith heptane are disclosed in U.S. Patent Application Publication No.2012/0157362 A1. Also, azeotropic and near azeotropic blends of methylperfluoroheptene ethers with ethanol are disclosed in U.S. PatentApplication Publication No. 2012/0157363 A1. Also, azeotropic and nearazeotropic blends of methyl perfluoroheptene ethers withtrans-1,2-dichloroethene are disclosed in U.S. Patent ApplicationPublication No. 2012/0227764 A1.

Further, azeotropic or near azeotropic blends of methyl perfluoropenteneethers with trans-1,2-dichloroethene, methanol, ethanol, 2-propanol,heptane, hexane, cyclopentane, ethyl formate, methyl formate, C₄F₉OCH₃,C₄F₉OC₂H₅, HFC-365mfc (CF₃CH₂CF₂CH₃) and/or 1-bromopropane are disclosedin International Patent Application Publication No. WO 2013/040266 A1.

In yet another embodiment of the high temperature heat pump apparatus,the working fluid comprises at least one alkyl perfluoroalkene ether andoptionally one or more fluids selected from the group consisting ofHFC-161, HFC-32, HFC-125, HFC-143a, HFC-245cb, HFC-134a, HFC-134,HFC-227ea, HFC-236ea, HFC-245fa, HFC-245eb, HFC-365mfc, HFC-4310mee,HFO-1234yf, HFO-1234ze-E, HFO-1234ze-Z, HFO-1336mzz-E, HFO-1336mzz-Z,HFO-1234ye-E or Z (1,2,3,3-tetrafluoropropene), HFO-1438mzz-E,HFO-1438mzz-Z, HFO-1438ezy-E, HFO-1438ezy-Z, HCFO-1233zd-E,HCFO-1233zd-Z, HCFO-1233xf, HFE-7000 (also known as HFE-347mcc orn-C₃F₇OCH₃), HFE-7100 (also known as HFE-449mccc or C₄F₉OCH₃), HFE-7200(also known as HFE-569mccc or C₄F₉OC₂H₅), HFE-7500 (also known as3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-trifluoromethyl-hexaneor (CF₃)₂CFCF(OC₂H₅)CF₂CF₂CF₃),1,1,1,2,2,4,5,5,5-nonafluoro-4-(trifluoromethyl)-3-pentanone (sold underthe trademark Novec™ 1230 by 3M, St. Paul, Minn., USA),octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane,octamethyltrisiloxane (OMTS), hexamethyldisiloxane (HMDS), n-pentane,isopentane, cyclopentane, hexanes, cyclohexane, heptanes, and toluene.

Of note are non-flammable compositions comprising at least one alkylperfluoroalkene ether. It is expected that certain compositionscomprising at least one alkyl perfluoroalkene ether and other compoundsas disclosed herein may be non-flammable by standard test ASTM 681.

Also of particular utility are any compositions wherein the workingfluid has a low GWP.

Any of the compositions comprising at least one alkyl perfluoroalkeneether may also comprise and/or be used in combination with at least onelubricant selected from the group consisting of polyalkylene glycols,polyol esters, polyvinylethers, mineral oils, alkylbenzenes, syntheticparaffins, synthetic naphthenes, perfluoropolyethers, andpoly(alpha)olefins.

Useful lubricants include those suitable for use with high temperatureheat pump apparatus. Among these lubricants are those conventionallyused in vapor compression refrigeration apparatus utilizingchlorofluorocarbon refrigerants. In one embodiment, lubricants comprisethose commonly known as “mineral oils” in the field of compressionrefrigeration lubrication. Mineral oils comprise paraffins (i.e.,straight-chain and branched-carbon-chain, saturated hydrocarbons),naphthenes (i.e. cyclic paraffins) and aromatics (i.e. unsaturated,cyclic hydrocarbons containing one or more rings characterized byalternating double bonds). In one embodiment, lubricants comprise thosecommonly known as “synthetic oils” in the field of compressionrefrigeration lubrication. Synthetic oils comprise alkylaryls (i.e.linear and branched alkyl alkylbenzenes), synthetic paraffins andnaphthenes, and poly(alphaolefins). Representative conventionallubricants are the commercially available BVM 100 N (paraffinic mineraloil sold by BVA Oils), naphthenic mineral oil commercially availablefrom Crompton Co. under the trademarks Suniso® 3GS and Suniso® 5GS,naphthenic mineral oil commercially available from Pennzoil under thetrademark Sontex® 372LT, naphthenic mineral oil commercially availablefrom Calumet Lubricants under the trademark Calumet® RO-30, linearalkylbenzenes commercially available from Shrieve Chemicals under thetrademarks Zerol® 75, Zerol® 150 and Zerol® 500, and HAB 22 (branchedalkylbenzene sold by Nippon Oil).

Useful lubricants may also include those which have been designed foruse with hydrofluorocarbon refrigerants and are miscible withrefrigerants of the present invention under compression refrigerationand air-conditioning apparatus' operating conditions. Such lubricantsinclude, but are not limited to, polyol esters (POEs) such as Castrol®100 (Castrol, United Kingdom), polyalkylene glycols (PAGs) such asRL-488A from Dow (Dow Chemical, Midland, Mich.), polyvinyl ethers(PVEs), and polycarbonates (PCs).

Lubricants are selected by considering a given compressor's requirementsand the environment to which the lubricant will be exposed.

Of note are high temperature lubricants with stability at hightemperatures. The highest temperature the heat pump will achieve willdetermine which lubricants are required. In one embodiment, thelubricant must be stable at temperatures of at least 55° C. In anotherembodiment the lubricant must be stable at temperatures of at least 100°C. In another embodiment, the lubricant must be stable at temperaturesof at least 125° C. In another embodiment the lubricant must be stableat temperatures of at least 150° C. Of particular note are poly alphaolefins (POA) lubricants with stability up to about 200-250° C. andpolyol ester (POE) lubricants with stability at temperatures up to about200 to 250° C. Also of particular note are perfluoropolyether lubricantsthat have stability at temperatures up to from about 220 to about 350°C. PFPE lubricants include those available from DuPont (Wilmington,Del.) under the trademark Krytox®, such as the XHT series with thermalstability up to about 300 to 350° C. Other PFPE lubricants include thosesold under the trademark Demnum™ from Daikin Industries (Japan) withthermal stability up to about 280 to 330° C., and available fromAusimont (Milan, Italy), under the trademarks Fomblin® and Galden® suchas that available under the trademark Fomblin®-Y or Fomblin®-Z withthermal stability up to about 220 to 260° C.

For high temperature condenser operation (associated with hightemperature lifts and high compressor discharge temperatures)formulations of working fluid (e.g. at least one alkyl perfluoroalkeneether) and lubricants with high thermal stability (possibly incombination with oil cooling or other mitigation approaches) will beadvantageous.

In one embodiment, the present invention includes a compositioncomprising: (a) at least one alkyl perfluoroalkene ether; and (b) atleast one lubricant suitable for use at a temperature of at least about100° C. Of note are embodiments wherein the lubricant is suitable foruse at a temperature of at least about 150° C. Also of note areembodiments wherein the lubricant is suitable for use at a temperatureof at least about 165° C. Also of note are embodiments wherein thelubricant is suitable for use at a temperature of at least about 175° C.Also of note are embodiments wherein the lubricant is suitable for useat a temperature of at least about 200° C. Also of note are embodimentswherein the lubricant is suitable for use at a temperature of at leastabout 225° C. Also of note are embodiments wherein the lubricant issuitable for use at a temperature of at least about 250° C.

In one embodiment, any of the composition

of this invention may further comprise 0.01 weight percent to 5 weightpercent of a stabilizer, free radical scavenger or antioxidant. Suchother additives include but are not limited to, nitromethane, hinderedphenols, hydroxylamines, thiols, phosphites, or lactones. Singleadditives or combinations may be used.

Optionally, in another embodiment, certain refrigeration,air-conditioning, or heat pump system additives may be added, asdesired, to the any of the working fluids as disclosed herein in orderto enhance performance and system stability. These additives are knownin the field of refrigeration and air-conditioning, and include, but arenot limited to, anti-wear agents, extreme pressure lubricants, corrosionand oxidation inhibitors, metal surface deactivators, free radicalscavengers, and foam control agents. In general, these additives may bepresent in the working fluids in small amounts relative to the overallcomposition. Typically concentrations of from less than 0.1 weightpercent to as much as 3 weight percent of each additive are used. Theseadditives are selected on the basis of the individual systemrequirements. These additives include members of the triaryl phosphatefamily of EP (extreme pressure) lubricity additives, such as butylatedtriphenyl phosphates (BTPP), or other alkylated triaryl phosphateesters, e.g. Syn-0-Ad 8478 from Akzo Chemicals, tricresyl phosphates andrelated compounds. Additionally, the metal dialkyl dithiophosphates(e.g., zinc dialkyl dithiophosphate (or ZDDP), Lubrizol 1375 and othermembers of this family of chemicals may be used in compositions of thepresent invention. Other anti-wear additives include natural productoils and asymmetrical polyhydroxyl lubrication additives, such asSynergol TMS (International Lubricants). Similarly, stabilizers such asantioxidants, free radical scavengers, and water scavengers may beemployed. Compounds in this category can include, but are not limitedto, butylated hydroxy toluene (BHT), epoxides, and mixtures thereof.Corrosion inhibitors include dodecyl succinic acid (DDSA), aminephosphate (AP), oleoyl sarcosine, imidazone derivatives and substitutedsulfphonates. Metal surface deactivators include areoxalyl bis(benzylidene) hydrazide,N,N′-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoylhydrazine,2,2,′-oxamidobis-ethyl-(3,5-di-tert-butyl-4-hydroxyhydrocinnamate,N,N′-(disalicyclidene)-1,2-diaminopropane andethylenediaminetetra-acetic acid and its salts, and mixtures thereof.

Any of the present compositions may include stabilizers comprising atleast one compound selected from the group consisting of hinderedphenols, thiophosphates, butylated triphenylphosphorothionates, organophosphates, or phosphites, aryl alkyl ethers, terpenes, terpenoids,epoxides, fluorinated epoxides, oxetanes, ascorbic acid, thiols,lactones, thioethers, amines, nitromethane, alkylsilanes, benzophenonederivatives, aryl sulfides, divinyl terephthalic acid, diphenylterephthalic acid, ionic liquids, and mixtures thereof. Representativestabilizer compounds include but are not limited to tocopherol;hydroquinone; t-butyl hydroquinone; monothiophosphates; anddithiophosphates, commercially available from Ciba Specialty Chemicals,Basel, Switzerland, hereinafter “Ciba,” under the trademark Irgalube®63; dialkylthiophosphate esters, commercially available from Ciba underthe trademarks Irgalube® 353 and Irgalube® 350, respectively; butylatedtriphenylphosphorothionates, commercially available from Ciba under thetrademark Irgalube® 232; amine phosphates, commercially available fromCiba under the trademark Irgalube® 349 (Ciba); hindered phosphites,commercially available from Ciba as Irgafos® 168; a phosphate such as(Tris-(di-tert-butylphenyl), commercially available from Ciba under thetrademark Irgafos® OPH; (Di-n-octyl phosphite); and iso-decyl diphenylphosphite, commercially available from Ciba under the trademark Irgafos®DDPP; anisole; 1,4-dimethoxybenzene; 1,4-diethoxybenzene;1,3,5-trimethoxybenzene; d-limonene; retinal; pinene; menthol; VitaminA; terpinene; dipentene; lycopene; beta carotene; bornane; 1,2-propyleneoxide; 1,2-butylene oxide; n-butyl glycidyl ether;trifluoromethyloxirane; 1,1-bis(trifluoromethyl)oxirane;3-ethyl-3-hydroxymethyl-oxetane, such as OXT-101 (Toagosei Co., Ltd);3-ethyl-3-((phenoxy)methyl)-oxetane, such as OXT-211 (Toagosei Co.,Ltd); 3-ethyl-3-((2-ethyl-hexyloxy)methyl)-oxetane, such as OXT-212(Toagosei Co., Ltd); ascorbic acid; methanethiol (methyl mercaptan);ethanethiol (ethyl mercaptan); Coenzyme A; dimercaptosuccinic acid(DMSA); grapefruit mercaptan((R)-2-(4-methylcyclohex-3-enyl)propane-2-thiol)); cysteine((R)-2-amino-3-sulfanyl-propanoic acid); lipoamide(1,2-dithiolane-3-pentanamide); 5,7-bis(1,1-dimethylethyl)-3-[2,3(or3,4)-dimethylphenyl]-2(3H)-benzofuranone, commercially available fromCiba under the trademark Irganox® HP-136; benzyl phenyl sulfide;diphenyl sulfide; diisopropylamine; dioctadecyl 3,3′-thiodipropionate,commercially available from Ciba under the trademark Irganox® PS 802(Ciba); didodecyl 3,3′-thiopropionate, commercially available from Cibaunder the trademark Irganox® PS 800;di-(2,2,6,6-tetramethyl-4-piperidyl)sebacate, commercially availablefrom Ciba under the trademark Tinuvin® 770;poly-(N-hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxy-piperidyl succinate,commercially available from Ciba under the trademark Tinuvin® 622LD(Ciba); methyl bis tallow amine; bis tallow amine;phenol-alpha-naphthylamine; bis(dimethylamino)methylsilane (DMAMS);tris(trimethylsilyl)silane (TTMSS); vinyltriethoxysilane;vinyltrimethoxysilane; 2,5-difluorobenzophenone;2′,5′-dihydroxyacetophenone; 2-aminobenzophenone; 2-chlorobenzophenone;benzyl phenyl sulfide; diphenyl sulfide; dibenzyl sulfide; ionicliquids; and others.

In one embodiment, ionic liquid stabilizers comprise at least one ionicliquid. Ionic liquids are organic salts that are liquid or have meltingpoints below 100° C. In another embodiment, ionic liquid stabilizerscomprise salts containing cations selected from the group consisting ofpyridinium, pyridazinium, pyrimidinium, pyrazinium, imidazolium,pyrazolium, thiazolium, oxazolium and triazolium; and anions selectedfrom the group consisting of [BF₄]—, [PF₆]—, [SbF₆]—, [CF₃SO₃]—,[HCF₂CF₂SO₃]—, [CF₃HFCCF₂SO₃]—, [HCCIFCF₂SO₃]—, [(CF₃SO₂)₂N]—,[(CF₃CF₂SO₂)₂N]—, [(CF₃SO₂)₃C]—, [CF₃CO₂]—, and F—. Representative ionicliquid stabilizers include emim BF₄ (1-ethyl-3-methylimidazoliumtetrafluoroborate); bmim BF₄ (1-butyl-3-methylimidazolium tetraborate);emim PF₆ (1-ethyl-3-methylimidazolium hexafluorophosphate); and bmim PF₆(1-butyl-3-methylimidazolium hexafluorophosphate), all of which areavailable from Fluka (Sigma-Aldrich).

EXAMPLES

The concepts described herein will be further described in the followingexample, which does not limit the scope of the invention described inthe claims.

Example 1 Heat Pump with Vertrel® HFX-110 as the Working FluidDelivering a Condensing Temperature of 200° C.

Vertrel® HFX-110 is a mixture of methyl perfluoroheptene ether isomersavailable from E.I. DuPont de Nemours & Co., Wilmington, Del., USA.Table 1 compares the performance of a heat pump operating with Vertrel®HFX-110 as the working fluid to the performance with n-heptane as theworking fluid. The heat pump is used to lift heat from an evaporatingtemperature of 150° C. to a condensing temperature of 200° C. Thecritical temperatures of Vertrel® HFX-110 and n-heptane are sufficientlyhigh to enable a condensing temperature of 200° C. The heat pump energyefficiency is quantified in terms of the Coefficient of Performance forheating, COP_(h), defined as the ratio of the heat delivered (includingcompressed vapor de-superheating, condensation and liquid sub-cooling)and the work of compression. The volumetric heating capacity, CAP_(h),is defined as the amount of heat delivered (including compressed vaporde-superheating, condensation and liquid sub-cooling) per unit volume ofworking fluid entering the compressor.

TABLE 1 Performance of a Heat Pump Operating with Vertrel ® HFX-110 asthe Working Fluid Compared to n-Heptane Vertrel ® HFX-110 vs. n-HeptaneHFX-110 n-Heptane (%) T_(cr) ° C. 267.0 240.0 T_(cond) ° C. 200 200T_(evap) ° C. 150 150 Superheat K 35 35 Subcool K 25 25 Compressor 0.70.7 Efficiency P_(cond) MPa 0.98 0.86 P_(evap) MPa 0.37 0.30 T_(disch) °C. 211.74 204.86 COP_(h) 7.269 7.573 4.2 CAP_(h) kJ/m³ 3,596.87 3,177.73−11.7

The heat pump performance for Vertrel® HFX-110 (COP_(h)=7.573;CAP_(h)=3, 177.73 kJ/m³) would be attractive. The energy efficiency (interms of COP) for heating with Vertrel® HFX-110 would be 4.2% higherthan with n-Heptane, while the volumetric heating capacity with Vertrel®HFX-110 would remain competitive. Moreover, Vertrel® HFX-110 isnon-flammable while n-Heptane is flammable. The compressor dischargetemperature with Vertrel® HFX-110 would be lower than with n-Heptane.The high discharge temperatures would require suitable materials ofequipment construction and suitable high-temperature lubricants (oroil-less compressors).

Example 2 Chemical Stability of Vertrel® HFX-110

The chemical stability of HFX-110 in the presence of metals was assessedaccording to the sealed tube testing methodology of ANSI/ASHRAE Standard97-2007. Sealed glass tubes, each containing three metal coupons made ofsteel, copper, and aluminum immersed in Vertrel® HFX-110, were aged in aheated oven at 225° C. for 7 days. The measured concentration offluoride ion in two aged liquid samples averaged 53 ppm, indicating thatthe degradation of HFX-110 was minimal. The sample purity after agingremained high and comparable to the purity of the unaged sample.

Selected Embodiments

Embodiment A1: A composition comprising at least one alkylperfluoroalkene ether selected from the group consisting of:

-   -   a) compounds of formula CF₃(CF₂)_(x)CF═CFCF(OR)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)C(OR)═CFCF₂(CF₂)_(y)CF₃,        CF₃CF═CFCF(OR)(CF₂)_(x)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)CF═C(OR)CF₂(CF₂)_(y)CF₃, or mixtures thereof,        wherein R can be either CH₃, C₂H₅ or mixtures thereof, and        wherein x and y are independently 0, 1, 2 or 3, and wherein        x+y=0, 1, 2 or 3 having the formula;    -   b) compounds of formulas CF₃(CF₂)_(x)CF═CFCF(OR)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)C(OR)═CFCF₂(CF₂)_(y)CF₃,        CF₃CF═CFCF(OR)(CF₂)_(x)(CF₂)_(y)CF₃,        CF₃(CF₂)_(x)CF═C(OR)CF₂(CF₂)_(y)CF₃, and mixtures thereof;        wherein x and y are independently 0, 1, 2, 3 or 4 and wherein        x+y=0, 1, 2, 3 or 4; and wherein R is        2,2,3,3-tetrafluoro-1-propyl, 2,2,3,3,3-pentafluoro-1-propyl,        2,2,2-trifluoro-1-ethyl, 2,2,3,3,4,4,5,5-octafluoro-1-pentyl, or        1,1,1,3,3,3-hexafluoro-2-propyl;    -   c) mixtures of compounds from (a) and (b).

Embodiment A2: The composition of Embodiment A1, wherein the alkylperfluoroalkene ethers comprise at least one of5-methoxyperfluoro-3-heptene, 3-methoxyperfluoro-3-heptene,4-methoxyperfluoro-2-heptene, 3-methoxyperfluoro-2-heptene, or mixturesthereof.

Embodiment A3: The composition of Embodiment A1, wherein the alkylperfluoroalkene ethers comprise at least one of4-methoxyperfluoro-2-pentene, 2-methoxyperfluoro-2-pentene,3-methoxyperfluoro-2-pentene, 2-methoxyperfluoro-3-pentene, or mixturesthereof.

Embodiment A4: The composition of Embodiment A1, wherein the alkylperfluoroalkene ethers comprise at least one of cis- andtrans-2-methoxyperfluoro-2-octene, 2-methoxyperfluoro-3-octene, ormixtures thereof.

Embodiment A5: The composition of any of Embodiments A1-A4, wherein theworking fluid further comprises at least one compound selected fromhydrofluorocarbons, hydrochlorocarbons, hydrofluoroethers,hydrofluoroolefins, hydrochlorofluorolefins, siloxanes, hydrocarbons,alcohols, perfluoropolyethers, and mixtures thereof.

Embodiment A6: The composition of any of Embodiments A1-A5, wherein theworking fluid comprises azeotropic or near-azeotropic mixtures.

Embodiment A7: The composition of any of Embodiments A1-A5, wherein theazeotropic or near azeotropic mixture comprises at least one methylperfluoroheptene ether and at least one compound selected from the groupconsisting of heptane, ethanol, and trans-1,2-dichloroethene.

Embodiment A8: The composition of any of Embodiments A1-A5, wherein theazeotropic or near azeotropic mixture comprises at least one methylperfluoropentene ether and at least one compound selected from the groupconsisting of trans-1,2-dichloroethene, methanol, ethanol, 2-propanol,heptane, hexane, cyclopentane, ethyl formate, methyl formate, C₄F₉OCH₃,C₄F₉OC₂H₅, HFC-365mfc, and 1-bromopropane.

Embodiment B1: A method for producing heating in a high temperature heatpump having a heat exchanger comprising extracting heat from a workingfluid, thereby producing a cooled working fluid wherein said workingfluid comprises A composition of any of Embodiments A1-A8.

Embodiment B2: The method of Embodiment B1, wherein the heat exchangeris selected from the group consisting of a supercritical working fluidcooler and a condenser.

Embodiment B3: The method of any of Embodiments B1 or B2, wherein theheat exchanger operates at a temperature of at least 55° C.

Embodiment B4: The method of any of Embodiments B1 or B2, wherein theheat exchanger operates at a temperature of at least 150° C.

Embodiment B5: The method of Embodiment B1, further comprising passing afirst heat transfer medium through the heat exchanger, whereby saidextraction of heat heats the first heat transfer medium, and passing theheated first heat transfer medium from the heat exchanger to a body tobe heated.

Embodiment B6: The method of Embodiment B5, wherein the first heattransfer medium is an industrial heat transfer liquid and the body to beheated is a chemical process stream.

Embodiment B7: The method of any of Embodiments B1-B6, furthercomprising expanding the working fluid and then heating the workingfluid in a second heat exchanger to produce a heated working fluid.

Embodiment B8: The method of Embodiment B7, wherein said second heatexchanger is an evaporator and the heated working fluid is a vapor.

Embodiment B9: The method of any of Embodiments B1-B7, furthercomprising compressing the working fluid vapor in a dynamic (e.g. axialor centrifugal) or a positive displacement (e.g. reciprocating, screw orscroll) compressor.

Embodiment B10: The method of Embodiment B9, wherein the dynamiccompressor is a centrifugal compressor.

Embodiment B11: The method of any of Embodiments B1-B10, furthercomprising passing a fluid to be heated through said condenser, thusheating the fluid.

Embodiment C1: A method for producing heating in a high temperature heatpump wherein heat is exchanged between at least two stages arranged in acascade configuration, comprising absorbing heat at a selected lowertemperature in a first working fluid in a first cascade stage andtransferring this heat to a second working fluid of a second cascadestage that supplies heat at a higher temperature; wherein the secondworking fluid comprises the composition of any of Embodiments A1-A8.

Embodiment D1: A method of raising the condenser operating temperaturein a high temperature heat pump apparatus comprising charging the hightemperature heat pump with a working fluid comprising the composition ofany of Embodiments A1-A8.

Embodiment D2: The method of Embodiment D1, wherein the condenseroperating temperature is raised to a temperature greater than about 150°C.

Embodiment E1: A high temperature heat pump apparatus containing aworking fluid comprising the composition of any of Embodiments A1-A8.

Embodiment E2: The high temperature heat pump apparatus of Embodiment E1wherein said apparatus comprises an evaporator, a compressor, acondenser or a supercritical working fluid cooler, and an expansiondevice.

Embodiment E3: The high temperature heat pump apparatus of any ofEmbodiments E1-E2, wherein the condenser or supercritical working fluidcooler operates at a temperature of at least 55° C.

Embodiment E4: The high temperature heat pump apparatus of any ofEmbodiments E1-E3 comprising a dynamic or a positive displacementcompressor.

Embodiment E5: The high temperature heat pump apparatus of any ofEmbodiments E1-E4 comprising a centrifugal compressor.

Embodiment E6: The high temperature heat pump apparatus of any ofEmbodiments E1-E4 comprising a screw compressor.

Embodiment E7: The high temperature heat pump apparatus of any ofEmbodiments E1-E6, said apparatus comprising (a) a first heat exchangerthrough which a working fluid flows and is heated; (b) a compressor influid communication with the first heat exchanger that compresses theheated working fluid to a higher pressure; (c) a second heat exchangerin fluid communication with the compressor through which the highpressure working fluid flows and is cooled; and (d) a pressure reductiondevice in fluid communication with the second heat exchanger wherein thepressure of the cooled working fluid is reduced and said pressurereduction device further being in fluid communication with theevaporator such that the working fluid then repeats flow throughcomponents (a), (b), (c) and (d) in a repeating cycle.

Embodiment E8: The high temperature heat pump apparatus of any ofEmbodiments E1-E7 having at least two heating stages arranged as acascade heating system, each stage circulating a working fluidtherethrough, wherein heat is transferred to the final orhighest-temperature stage from the preceding stage and wherein theheating fluid of the final stage comprises at least one alkylperfluoroalkene ether.

Embodiment E9: The high temperature heat pump apparatus of any ofEmbodiments E1-E8 having at least two heating stages, a first orlower-temperature stage and a second or higher-temperature stage,arranged as a cascade heating system, each stage circulating a workingfluid therethrough comprising (a) a first expansion device for reducingthe pressure and temperature of a first working fluid liquid; (b) anevaporator in fluid communication with the first expansion device havingan inlet and an outlet; (c) a first compressor in fluid communicationwith the evaporator and having an inlet and an outlet; (d) a cascadeheat exchanger system in fluid communication with the first compressoroutlet having (i) a first inlet and a first outlet, and (ii) a secondinlet and a second outlet in thermal communication with the first inletand outlet; (e) a second compressor in fluid communication with thesecond outlet of the cascade heat exchanger system and having an inletand an outlet; (f) a condenser in fluid communication with the secondcompressor and having an inlet and an outlet; and (g) a second expansiondevice in fluid communication with the condenser; wherein the secondworking fluid comprises at least one alkyl perfluoroalkene ether.

Embodiment E10: The high temperature heat pump apparatus of any ofEmbodiments E8-E9, wherein the first or lower-temperature stage workingfluid comprises at least one fluoroolefin or chlorofluorolefin selectedfrom the group consisting of HFO-1234yf, E-HFO-1234ze, E-HFO-1234ye-E orZ, HFO-1243zf, HFO-1234ze-Z, HFO-1336mzz-E, HFO-1336mzz-Z,HFO-1438mzz-E, HFO-1438mzz-Z, HFO-1438ezy-E, HFO-1438ezy-Z, HFO-1336yf,HFO-1336ze-E, HFO-1336ze-Z, HCFO-1233zd-E, HCFO-1233zd-Z, andHCFO-1233xf.

Embodiment E11: The high temperature heat pump apparatus of any ofEmbodiments E8-E10, wherein the first or lower-temperature stage workingfluid comprises at least one fluoroalkane selected from the groupconsisting of HFC-161, HFC-32, HFC-125, HFC-245cb, HFC-134a, HFC-134,HFC-143a, HFC-152a, HFC-161, HFC-227ea, HFC-236ea, HFC-245fa, HFC-245eb,HFC-365mfc, and HFC-4310mee.

Embodiment E12: The high temperature heat pump apparatus of any ofEmbodiments E8-E11, wherein the working fluid of the stage preceding thefinal or highest-temperature stage comprises at least one fluoroolefinor chlorofluorolefin selected from the group consisting of HFO-1234yf,E-HFO-1234ze, E-HFO-1234ye-E or Z, HFO-1243zf, HFO-1234ze-Z,HFO-1336mzz-E, HFO-1336mzz-Z, HFO-1438mzz-E, HFO-1438mzz-Z,HFO-1438ezy-E, HFO-1438ezy-Z, HFO-1336yf, HFO-1336ze-E, HFO-1336ze-Z,HCFO-1233zd-E, HCFO-1233zd-Z, and HCFO-1233xf.

Embodiment E13: The high temperature heat pump apparatus of any ofEmbodiments E8-E12, wherein the working fluid of the stage preceding thefinal or highest-temperature stage comprises at least one fluoroalkaneselected from the group consisting of HFC-161, HFC-32, HFC-125,HFC-245cb, HFC-134a, HFC-134, HFC-143a, HFC-152a, HFC-161, HFC-227ea,HFC-236ea, HFC-245fa, HFC-245eb, HFC-365mfc, and HFC-4310mee.

Embodiment E14: The heat pump apparatus of any of Embodiments E8-E13,wherein the first or lowest-temperature stage working fluid comprises atleast one working fluid selected from CO₂ or N₂O.

Embodiment F1: A method for supplying simultaneous heating and coolingin a cascade heat pump system comprising providing a low temperaturecascade stage containing a working fluid selected from the groupconsisting of CO₂, N₂O, HFC-161, HFC-32, HFC-125, HFC-143a, HFC-245cb,HFC-134a, HFC-134, HFC-152a and HFC-227ea, HFC-236ea, HFC-245fa,HFC-245eb, HFC-365mfc, HFC-4310mee, HFO-1234yf, HFO-1234ze-E,HFO-1243zf, HFO-1234ze-Z, HFO-1336mzz-E, HFO-1234ye-E or Z(1,2,3,3-tetrafluoropropene, E- or Z-isomer), HFO-1336mzz-Z,HFO-1438mzz-E, HFO-1438mzz-Z, HFO-1438ezy-E, HFO-1438ezy-Z, HFO-1336yf,HFO-1336ze-E, HFO-1336ze-Z, HCFO-1233zd-E, HCFO-1233zd-Z, HCFO-1233xf,5-methoxyperfluoro-3-heptene, 3-methoxyperfluoro-3-heptene,4-methoxyperfluoro-2-heptene, 3-methoxyperfluoro-2-heptene,4-methoxyperfluoro-2-pentene, 2-methoxyperfluoro-2-pentene,3-methoxyperfluoro-2-pentene, 2-methoxyperfluoro-3-pentene, cis- andtrans-2-methoxyperfluoro-2-octene, 2-methoxyperfluoro-3-octene andmixtures thereof; and providing a high temperature cascade stagecontaining a working fluid comprising at least one alkyl perfluoroalkeneether; wherein said low temperature cascade stage and said hightemperature cascade stage are in thermal contact.

Embodiment G1: A composition for use in high temperature heat pumpscomprising (i) a working fluid consisting essentially of the compositionof any of Embodiments A1-A8; and (ii) a stabilizer to preventdegradation at temperatures of 55° C. or above; or (iii) a lubricantsuitable for use at 55° C. or above, or both (ii) and (iii).

1-11. (canceled)
 12. A method for producing heating in a hightemperature heat pump wherein heat is exchanged between at least twostages arranged in a cascade configuration, comprising: absorbing heatat a selected lower temperature in a first working fluid in a firstcascade stage and transferring this heat to a second working fluid of asecond cascade stage that supplies heat at a higher temperature; whereinthe second working fluid comprises at least one alkyl perfluoroalkeneether. 13-24. (canceled)
 25. The method of claim 12, wherein said secondworking fluid comprises at least one alkyl perfluoroalkene etherselected from the group consisting of: a) compounds of formulaCF₃(CF₂)_(x)CF═CFCF(OR)(CF₂)_(y)CF₃,CF₃(CF₂)_(x)C(OR)═CFCF₂(CF₂)_(y)CF₃,CF₃CF═CFCF(OR)(CF₂)_(x)(CF₂)_(y)CF₃,CF₃(CF₂)_(x)CF═C(OR)CF₂(CF₂)_(y)CF₃, or mixtures thereof, wherein R canbe either CH₃, C₂H₅ or mixtures thereof, and wherein x and y areindependently 0, 1, 2 or 3, and wherein x+y=0, 1, 2, or 3; b) compoundsof formulas CF₃(CF₂)_(x)CF═CFCF(OR)(CF₂)_(y)CF₃,CF₃(CF₂)_(x)C(OR)═CFCF₂(CF₂)_(y)CF₃,CF₃CF═CFCF(OR)(CF₂)_(x)(CF₂)_(y)CF₃,CF₃(CF₂)_(x)CF═C(OR)CF₂(CF₂)_(y)CF₃, and mixtures thereof; wherein x andy are independently 0, 1, 2, 3 or 4 and wherein x+y=0, 1, 2, 3 or 4; andwherein R is 2,2,3,3-tetrafluoro-1-propyl,2,2,3,3,3-pentafluoro-1-propyl, 2,2,2-trifluoro-1-ethyl,2,2,3,3,4,4,5,5-octafluoro-1-pentyl, or 1,1,1,3,3,3-hexafluoro-2-propyl;and c) mixtures of compounds from (a) and (b).
 26. The method of claim12, wherein the second working fluid comprises at least one alkylperfluoroalkene ether selected from the group consisting of5-methoxyperfluoro-3-heptene, 3-methoxyperfluoro-3-heptene,4-methoxyperfluoro-2-heptene, and 3-methoxyperfluoro-2-heptene, ormixtures thereof.
 27. The method of claim 12, wherein the second workingfluid comprises at least one alkyl perfluoroalkene ether selected fromthe group consisting of 4-methoxyperfluoro-2-pentene,2-methoxyperfluoro-2-pentene, 3-methoxyperfluoro-2-pentene, and2-methoxyperfluoro-3-pentene, or mixtures thereof.
 28. The method ofclaim 12, wherein the second working fluid further comprises at leastone compound selected from a hydrofluorocarbon, a hydrochlorocarbon, ahydrofluoroether, a hydrofluoroolefin, a hydrochlorofluorolefin, asiloxane, a hydrocarbon, an alcohol, and a perfluoropolyether, ormixtures thereof.
 29. The method of claim 28, wherein the second workingfluid comprises an azeotropic or near-azeotropic mixture.
 30. The methodof claim 29, wherein the azeotropic or near azeotropic mixture comprisesat least one methyl perfluoroheptene ether and at least one compoundselected from the group consisting of heptane, ethanol, andtrans-1,2-dichloroethene.
 31. The method of claim 29, wherein theazeotropic or near azeotropic mixture comprises at least one methylperfluoropentene ether and at least one compound selected from the groupconsisting of trans-1,2-dichloroethene, methanol, ethanol, 2-propanol,heptane, hexane, cyclopentane, ethyl formate, methyl formate, C₄F₉OCH₃,C₄F₉OC₂H₅, HFC-365mfc, and 1-bromopropane. 32-33. (canceled)
 34. Themethod of claim 12, wherein the second working fluid comprises at leastone alkyl perfluoroalkene ether selected from the group consisting ofcis- and trans-2-methoxyperfluoro-2-octene, 2-methoxyperfluoro-3-octene,or mixtures thereof.